I'm a little uncertain exactly what part of the quoted text you are objecting to, but there are generally two arguments given for why gays shouldn't be parents, teachers, scoutmasters, etc. a) They will try to convert or otherwise influence children to "turn gay" and, b) they are disproportionately likely to be pedophiles. The arguments for DADT are generally a little different, but there's definitely a thread there that includes the same idea that gays will be unable to resist making sexual advances on their fellow soldiers.
Point A comes from the fear that their children will turn gay because they have a gay person in their life. (Which would imply that children become janitors just because they have janitors around them...)
But for point B, is there scientific evidence for it?
This is highly anecdotal, but I have a few gay friends who served in the military, and they all said that the straight guys had more gay sex than them.
The explanation isn't that weird though. If you're straight you can always dismiss it, it's not "real", it's just because of this weird situation living with only guys for some time, and out in real life you're as straight as they come. But for gay guys, it is real, so you're a lot more careful about something that might develop into a relationship.
