I'm pretty sure there are several (new, mind you, and possibly made-up) terms for the scenario which you describe, thanks to the anti-labeling movement that's risen up on the internet in the recent years. In other words, neither.
If a male could be attracted to other males, then what defines him is whatever he wants to define himself as. One might argue that he's not hetero because there's the possibility of going beyond heterosexualism, but in the end, if he chooses to say he's hetero, there's not really that big of a need to contradict him, i guess.