You can't be friends with a girl either. Either you marry her or just stay away from her. You can't just stay with her and waste her time or find ways to abuse her in a horrible relationship. Before you continue on with your "friendship" I advice for you to stay away from her unless she really needs the help.
Like... objectifying her is one thing man. Just because she is a girl, it doesn't mean you should friend her so that you can maybe brag about her to others. Or make yourselves seem like a "popular" kid who is surrounded by many ladies.
Would you be happy with a man fooling around your girl? Also how did other people know that a girl is playing? Don't you know how a man look at a woman? Woman can't just announce that she is a woman in an environment mostly incorporated of man. Of course, if a man has only seen a man around him, if a girl appears, many man will react. Some will try to come close to her(perhaps what you did but instead in real) and some will attack her not knowing what to do with her sudden appearance.
To think that a man will not react in any way when a woman barge into their lives suddenly when a game is mostly man is very sexist. Man likes what is beautiful. Woman is beautiful and many man desire to have a woman. So, in an environment when a beautiful woman is never seen and suddenly is seen, man will naturally look at her.
I have no clue what is so confusing about this to you. A man will react this way of course. Maybe not in the same way, but will show some reaction regardless. The same way you approached her in the first place and perhaps told her about this game so that you can come closer to her. Though, if you will marry her, then GO AHEAD. But if you aren't and just using her as your past time, then just leave. This is for you and the girl's good.
What the guy said was inappropriate but to have empathy even for these people is what makes people... people. You are very mean if you simply look at the world through your own perspective and ignore others. Thinking as though you are perhaps "perfect"... perhaps arrogance is in there somewhere? Woman should not make her appearance in a male dominant area. She has her place of dominance and so does man. Woman should not force herself into a male area except through necessity.