My point is, I can understand why a heterosexual female would be uncomfortable showering with a heterosexual male; teammate, coworker, stranger, or otherwise.
If I understand the source of that discomfort, then I can also understand a straight male athlete being uncomfortable showering with a homosexual male. To me it's the same thing and both heterosexual males and heterosexual females have the same right to refuse to shower with someone who's sexual orientation sets it up that way.
If a girl is comfortable showering with straight men, gay men, straight women, gay women. Cool. More power to her. But I would understand why any of those scenarios would make her uncomfortable and she would have the right not to be forced into doing that.
Same applies for men. If you're a married and faithful man, you might not be comfortable with straight women in your shower room. If you're an athlete you may want to be fully dressed before you see the media and have the right not to allow female reporters not to see u naked.
The answer isn't that Jason Collins should shower separately or anything - but I think that straight male athlete has a legitimate concern and right not to want to shower with Jason Collins.