Not to get too deep into this because at a certain point, an adult son's sexuality is not his mother's business... However, I will share with you that it could be the case that the abuse has affected your son's arousal template.
Which is to say: that thing he has for older men? It might never go away. I appreciate your concerns for him and your desire to protect him, and certainly there are a few of us here who could have benefitted from a mother who knew what we were up to at 18...
However, there's a downside to this as well. You don't want him thinking you are helicoptering over him and interfering with his life, even though you have the best intentions.
Edit: To follow up on Lancer's post above: it is critical for him to know that you won't be reading his posts here. Tell him that you come to the Friends&Family forum to post and that you don't look at other forums or other posts, and then follow through with it. Like Lancer said, you should not know what your son's user name is here. If he thinks his posts are getting read, he will self-censor himself and dilute his recovery.
Edited by cant_remember (02/27/13 12:17 PM)
"There is a Catskill eagle in some souls that can alike dive down into the blackest gorges, and soar out of them again and become invisible in the sunny spaces... even in his lowest swoop the mountain eagle is still higher than other birds upon the plain, even though they soar." -- from Moby-Dick