This was my reaction, too. I consider myself gay-tolerant and have gay friends, and my sense is that my college's frats (this, in the late 80s) probably all had the following:
1. a few openly gay members (albeit none who were agitators or the like); and
2. a few members who, whatever they were "then," are now living as gay.
None of the frats would have drummed someone out for being gay. If you were Richard Simmons-ey, you might not have gotten a pledge, but that would be because you were annoying as hell, which could be said of a lot of straight guys too.
Point is, I fail to see the good in a frat whose membership revolves around sexual orientation. Sounds like another effort at self-segregation, a la "the black house(s)," etc.
It's all about attention.