If you have a preference for heterosexual men then that's fine. You should perhaps ask him and tell him this though so he can tell you if he has or not and so he can choose if he would still want to continue the relationship or not.
Would it be any better in that regard if he's had sex with a lot of women?
Instead ask about if he's ever been tested or if he's been safe in the past if that's what you're worried about. Or better yet, take precautions regardless.