😂 Then it's not an LGBT birthday cake is it?! If the cake said, "To Sarah, Happy Birthday from your wife" A perfectly reasonable message, they'd be denied service. Again, this is nothing like asking everybody, regardless of faith or sexuality or anything else, to put their alcohol in a bag.
You could even make the case that the Muslim drivers should be required to provide bags for customers to put their alcohol into if they didn't have a bag of their own. I'd think it was silly, but I could see the logic.
But pretending open-carrying alcohol is equivalent to being gay is just trolling. Which I'm not going to waste further time on.