If a woman gets raped and you tell her "oh well maybe you shouldn't have worn that clothing" then yeah, that's victim blaming.
But if she does it with the intention of getting raped so that she can bring attention to herself, then yeah, she's responsible.
Of course, the latter situation is a ridiculous concept, but...that's what the social media post the restaurant posted is comparable too.
You've had restaurants like Chik-Fil-A, who are just like "yeah we support traditional marriage k thx", and some people have chosen to boycott them for that, but they've remained a successful chain. But this restaurant didn't do that. The way they hit pretty much every hot button political issue, and then top it off with a "if you disagree, tell 100 of your friends and don't come back", it really sounds to me like they were deliberately trying to stir up a controversy, and bank off the "no publicity is bad publicity mindset"
That's why it's not victim blaming.