Outlier, I think it's great that you're asking genuine questions and wanting to learn more, even when your instinctive position may be that you don't agree with parts of this discussion. Open-mindedness is key.
Re dressing rooms, the main point is that women are more likely to feel sexually threatened or self-conscious with men around, so they need their own space. Men aren't likely to feel threatened by women. It could be embarrassing but In professional sports men tend to walk around locker rooms and showers in front of female journalists, medicos and so on without a worry. I can't see any reason for men to feel threatened by gay teammates.
Disapproving of homosexuality might not manifest in an aggressive way, but it does still send a message that the person is sinful or wrong, when they're not doing anything to deserve that. Being gay isn't a 'lifestyle', you either are or you aren't. If it were a choice, it's hard to imagine people would choose the undoubtedly more difficult life.
Also good to have some thoughts from a former AFL player on the issue, so this article is a good contribution, and a very balanced one.
It's a minor problem for those of us who never experience it, yes.