Good question Sue, but I don't agree with your answer. I think that if they spotted Alma watching, given what we know about Ennis and how he behaves, I think he would've pushed Jack away, slugged him in the face, maybe kicked him when he was down, and then told Alma about how this "queer" force himself on to him.
This thread began by wondering about Laureen, then Alma, and now about the guys, specifically how they would have reacted had they realized at the reunion that they had been spotted by Alma. This does give us more room to operate since both story and movie tell us more about them than about the women. Before that, however, I want to ask about Ennis' supposed "internalized homophobia" that has led so many people here to blame it for Ennis' failure to act.
When most of us think of homophobia, we think of people with the kind of behaviour that gives us the so-called "homophobic panic" used in the past to justify thugs in bashing cases, of bullying, bashings, killings, fag jokes, ex-gay conversion groups, religious right-wing crazies threatening us with hell and damnation, and the like. Is there really any evidence to count Ennis amongst their number?
Ennis makes it clear, from the reunion on, that the reason he will not live with Jack is that he is afraid of getting killed. This is why he tells the Earl and Rich story in the first place. He expresses no homophobic attitude towards Rich and Earl, nor at anyplace does he say or do homophobic things. Along with his fear of being killed by living with Jack, is his worry that any actions in public that make his feelings towards Jack obvious will lead to the same thing. He has a pretty good case--discretion is the better part of valour, especially in that time and that place. He does seem to have the idea that if they put themselves in situations where they could be found out, that no matter how careful they are, it is bound to happen. At no point does he express any real homophobic behaviour in the sense that we usually use the word. The worst we can accuse him of is being paranoid, but the Earl and Rich story and his perceived belief about how Jack died would justify any paranoia rather than undercut it.
Regarding paranoia, consider how Ennis changes. In the tent the first night, Jack initiates the encounter, but Ennis becomes an enthusiastic partner very quickly. On the second night, Ennis acts perhaps more bravely than he does at any other time when he chooses to get up from the fire and walk into the tent--he is not acting to counter any internalized homophobia, but rather his fears that what he is about to do might well lead to his death. In succeeding days--as suggested in the movie by the Aguirre-with-binoculars scene, and in the story by Proulx's saying much about their having a lot of sex both in the tent and out in the open--Ennis takes a lot of chances. Out in the open, when at any time a stranger could wander by? I wouldn't have done it.
Fast forward to the reunion. They embrace, but Ennis is the one (in the movie) who looks around slyly, and pulls Jack to a more private place and begins the kissing sequence. This is a long way from "a one-shot thing we got going." If there is any place where Ennis could be perceived as homophobic it is in the final argument when he says the "boys like you" line. But at that point neither man is speaking entirely rationally, both are pushing the other's buttons to wound the other in misguided self-defense. The final argument ranges from Jack's "a goddam bitch of an unsatisfactory situation" and "I wish I knew how to quit you" to Ennis "You been to Mexico, Jack Twist? I know what they got in Mexico ( in the movie) for boys like you." This is mild stuff indeed for a rampant homophobe.
Ennis is certainly carrying around a lot of emotional baggage which will never allow him to step beyond it and chance death by being open about his love for Jack. But we shouldn't sum up all that emotional baggage as "internalized homophobia." That is inaccurate and discounts Ennis' character. Ennis does not say much about his first 18 years, but they couldn't have been nice. If we want to account for Ennis' fears and doubts, we have to look there, but we can't. All we've got to go on is what the movie and story have to tell us.
Back to the reunion and how the men might have reacted if they had known they were caught out. I suggest they did know, at least partially. Here the difference between the movie and story are important. In the movie the reunion scene happens outside, and Alma opens the door once. In the story it happens inside in a darkened hallway outsiide the apartment, and Alma opens the door a second time. We can assume that essentially the same behaviour between the two men happened in the hall as happened outside--the embrace, the passionate kissing, the conclusion with Ennis reluctantly pushing Jack away to calm things down, but both still consumed with sexual passion and frustration. (Check out Jack's face when Ennis has to push him away and tell him to slow down.) Alma first opens the door for a few seconds as the two are kissing. She opens it again when they have stopped, but are still standing virtually on top of one another, still obviously hot and bothered. When "The door opened again a few inches and Alma stood in the narrow light," Ennis sees this and realizes what she has seen. "What could he say? 'Alma, this is Jack Twist, Jack, my wife Alma'...'Alma' he said, 'Jack and me ain't seen each other in four years.' As if it were a reason. He was glad the light was dim on the landing but did not turn away from her."
Ennis is not good at verbal footwork. I think he realized she was on to them, but he didn't much care. It certainly didn't stop them from getting to the motel as soon as possible. In the Thanksgiving scene when he responded with anger to Alma's "Jack Nasty" line, and he threatens to make Alma and Monroe "eat the fuckin floor" if she doesn't back off, there is no "I'm straight, he's queer" or verbal attacks on Jack or gays to bolster his straight credentials. And no real denial of what she knows. He just leaves in anger and goes out and gets drunk. If you remember Queer as Folk, contrast Ennis reaction to that of Chris Hobbs when Justin confronts him in public about the hand job. That did indeed almost lead to someone's death.
I am left with the belief that Ennis is the tragic figure in BBM, that the biggest mistake of his life was not settling down with Jack, but this was not because Ennis was homophobic, but a very screwed up man, probably because of his childhood--what else could it be?--never able to free himself, and because of it, five people's lives were harmed.
