First of all, I don't want to make it sound like it's all her. I wouldn't feel great about going there either. I'm a little more forgiving than she is, but I still feel strongly about this subject.
Anyway, it is definitely not the depictions themselves. It's the transphobic message of the signs. They insist that only those with penises can be men and use the men's room, and only those with vaginas can be women and use the women's room.
That alone was enough to irk her, but I think she could have gotten over it if not for the notes now hung over the signs, which are worse. Don't pretend to apologize for your shitty signs when you clearly aren't sorry. It's like telling someone "I'm sorry that's how you feel." That isn't an apology, that's a **** you.
And like everybody in this country, they're entitled to their opinion, and they can conduct business however they please, and alienate whomever they please. But to me this is the same as walking into a pizza place and seeing a sign that says "This is America, Speak English or Get Out!" So yeah, no hard feelings, I have friends that go and love the place, and I don't give them grief about it and never will, but that place just isn't for me.