The fact is still that the gay panic defense was recently used and can be used successfully in Texas.
Yes, it has. It's been used in a multitude of states such as, but not limited to, California, Florida, Michigan, Mississippi, Nebraska, Utah, etc.
It is usually unsuccessful not because the states don't permit the defense, but because setting aside the legality, it's a shit defense and hard to prove it out. Usually the person claiming gay panic ends up with some testimony against them that they either engage in some gay behavior themselves, have been propositioned before without attacking someone, have other circumstances at play like being drunk, etc.
I firmly stand by my statement... this is a national issue and one that the LGBT bar has been fighting. If you want to make it out to be a problem limited to Texas, you can. You'd be stupid and wrong-headed, but you certainly can.