Of course it is.
I was married twice, have you been married? If so did anyone require you to "prove" your gender?
They took my wives' and my word for it.
""Is this legalizing Gay Marriage?"
Of course it is."
Yep. That is the whole purpose of this. Very crafty. If Bruce and Stan want to marry all one of them has to do is have their sex changed on their birth certificate and bingo.
Can't redefine marriage? Then redefine gender.