re: I wonder if Leftists would defend a Muslim baker if...

I'm more of a Libertarian but I absolutely would defend it. I would also defend the Christian bakery. If a business doesn't want to bake for someone, they shouldn't be forced to. Let the free market hand said business if they don't like the way they choose to run their business.

I wouldn't spend my money there but they should have the right to live up to their religious beliefs as long as they are a private company.