However, free speech has consequences. This probably isn't a Constitutional matter, but she absolutely has the right to do this. They absolutely have the right (I'm pretty sure) to fire her.
So, I'm sympathetic but not surprised. Freedom of expression should be more than a part of the Constitution, it should be a societal goal. I'd much prefer a world where off-duty expression doesn't risk your employment but that's not up to me.
Err... Who are these 'free speech folks' that you're thinking of? We used to just call those people by the name, 'Americans.' The liberty of free speech applies to all, or none.
All along, our central argument has been that the pendulum swings both ways. The same means which are used to silence the one side will work just as well against the other. That is free speech's raison d'être.