Hmm he could be closeted with friends/family and finds work a new outlet for him to "be himself", is my worry...
From my experience talking about personal lives at work has always been part of the getting to know everyone package
[*shoos DemolitionRed's coworker away before he can say "getting to know everyone's package more like ooooo!!"*] so it's not really that unusual to know if someone's seeing someone, is gay, has kids, has just lost a relative, or whatever, so I don't really know why that'd be an issue
I agree with AnnieK though that just a gentle reminder of workplace conduct (ESPECIALLY with the 'fainting over men' thing, definitely a slippery slope to sexual harassment) from higher people would be fine. From someone like you it could sound condescending and give him grounds to shirk responsibility and accuse you of homophobia or whatever.