Not sure if this helps, but there is a huge bisexual culture out there. I ran into a guy not so long ago who spend a great deal of time literally illustrating to me that he was bisexual and yet he preferred a relationship with a woman. It was a bit of a hard pill to swallow. But it opened me up to the idea. This is just one of many prejudices our culture holds.
Him having had prior relationships with men is no different from him having had prior relationships with other women. I'm new to the idea of dealing with CSA and it's effects, but I would think that sexual exploration is a healthy thing. And I would further think that not being judged for past curiosities would be even healthier thing.