I've seen a couple of people answer saying "If a guy says he is Bi-ual : He is gay!" Do you agree?

NO,I don't agree as I know some ppl can be and they have attraction towards to both and successfully can have with both ..but I never understand that straight guy want to have with another guy and still considers himself a straight..that's stupid.if straight guys having bj even for a once then he is not straight.straight guy shouldn't even have thought of having bj from guy's mouth..