It's not really "the GOP". It's a sect of the GOP that's being criticized by many in the GOP. Look at Arizona; the bill was vetoed for a second time.
Yes, but this bill has passed both the house and the senate. And republicans haven't a solid majority: 17-13 in the senate. So, few defections. It's not only a part of the GOP, it's definitely a large part of elected republicans.
The elected Republicans are scared and pandering to the Tea Party.
Of course. I definitely believe that Republicans voters aren't a majority of homophobic, but Republicans elected: yes. The Tea Party is definitely not a minority or a sect, it is definitely an important majority of the GOP elected officials.
I don't even know that I agree that it's a majority of the elected GOP officials. I just think a majority of elected GOP officials pander to them to get elected / stay in office.