Speaking from my own experience the answer to your question is probably all of the above; shame, questions or doubting of his sexual identity, guilt, lack of libido, attraction to men, etc. It should be noted that sexual identity confusion is not necessarily the same as gay or homosexual. There are many heterosexual or straight sexual abuse survivors who have same sex attractions. Attraction does not necessarily mean orientation but it can.
"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting 'Holy Shit! What a ride!'" ~Hunter S. Thompson