They tend to by Players! I would not think that a man or male that is seeing a number of females should be classified as homosexual as the word homo is homogeneous or alike. There may be men that have sex with many women and also men they usually end up getting some type of STD. But individuals that sleep around usually do end up with the down-side case of why discretion is the key as is safe and responsible practices. If you are having sexual relations with someone that is promiscuous then it would be wise to stop fooling around with that person as a cheater will always be a cheater, it is their nature and the only one that can stop them is them. You will end-up with a lot of heart-ache if you think they will change for you. They will share the side-affects of being indiscreet with you.
If he is sleeping with all of these women, then no he is not gay or trying to hide it. Just too much testosterone for his own good. If he were going out with these girls in a group, well then he very well may be gay. Or if he say goes to get his nails done with his girlfriends and that sort of thing. Does he sing show tunes?
I would think that he just has a strong desire to be with a woman sexually or he likes to be in the presence of a lot of different women. If he liked men he would not have the desire to be with women.
I know a guy who maintained several long distance relationships with women (the women each thought they were serious and exclusive) for years, while sleeping with men as well. He was also into weird S&M stuff. That guy was totally messed up and he has ruined several lives, I think he might be a closeted homosexual.