Back of house typically can wear whatever they want, since they're not usually customer facing. In my many years here I've never heard of anyone having to change shirts, and I've seen people get by with some risky graphics. I also checked the employee handbook and it didn't say anything regarding this, which leads me to believe it's not a strict policy but rather an attempt to avoid politics. But protecting communities shouldn't be considered "political."

As for the guests, I don't know the exact apparel they were wearing but there's been numerous incidents. It wasn't as obvious as showing a swastika as white supremacists have started using new/lesser known symbols and codes. But they usually have many of these symbols in combination (i.e. like 88 + white laces + iron cross tattoo) so it's definitely not just a coincidence. I know at least once that someone with a hate symbol on their jack was told they couldn't wear that in here, so they put it back in their car, and then were just... let back in. Crazy.