And there we go again! Five minutes ago there was a molehill, now there's a mountain! The bakers had been perfectly happy to serve ordinary products to these customers before. I find it hard to believe that they did not know the customers were part of the LGBTQ+ community and in the ordinary way this apparently didn't bother them. There are people who have no objections to LGBTQ+ people per se, but do have set ideas on the nature of marriage and what it should be. Clearly this one request crossed a line with them and they declined it. The sensible route would have been for the couple to find another baker - most other businesses would have looked at the bottom line and be damned to morals, we both know that!
But instead they decided to make a fuss, and it is that which might very well lead to the situation you describe. People who previously might not have bothered about such things now will because either the customers' or the bakers' attitude has pissed them off. A case of opponents squaring off for a duel, then both promptly shooting themselves in the foot!
The 'you have to serve everyone regardless' idea leaves businesses - especially the proprietors of small ones- - vulnerable to all kinds of abuse. It also is one more step in the erasure of the concept of personal integrity and freedom of thought.
I don't agree with the stance of the baker, but I am not going to force him to abandon his beliefs to suit the convenience of people who could easily find another person to provide their cake. If he were a teacher who refused to teach the adopted child of a gay couple, then I'd demand he be fired, because there's a Hell of a difference between providing necessary education and baking an indulgent cake!
The more we fixate on the trivla and ignore the vital, the sillier things will get!