my AIDS medical sources say even sucking ain't good - in that place and time, they had no way to gauge the virulity of contagion and oral sex was widely discouraged.
If there are any other gay 80's survivors who want to weigh in... one thing to remember is that Nick is the son of a doctor, and has some of the sensibilities drilled into him about disease from Dear Old Dad.
And I don't find it too graphic, David - anybody else? After all, we survived "Wedding Tackle."