Me, too. Because notice (and I think it was you who first pointed this out, LJ), Jack didn't give that ranch neighbor of his a name when mentioning him to Old Man Twist.
I see Jack going up to Lightning Flat to see the folks for a few days after leaving that last campsite, and I see Old Man Twist saying something snide to him about Ennis (e.g., "Whatever happened to that Ennis Del Mar you always used to mention? Just another one of those ideas of yours that never come to pass?") and him retorting with something like, "The hell with him. I got another friend now - ranch neighbor of mine - gonna come up here with me." And I can see him saying that regardless of whether he and Randall were still/ever were an item just to shut his father up.
To me, the tragedy is all the more heart-wrenching in that Ennis was starting to have a change of heart and that had Jack made him an ultimatum on that November 7 reunion that never came to pass, he might not have let him go. But maybe I'm just thinkin' out loud.