You can't tell the difference between someone participating in an immoral act and commissioning a private business to participate in such, via its products. Methinks the "stupid and ridiculous" tag fits your arguments.
Oh brother... Let's take it from the top, shall we?
There's no rational explanation in a pizza store claiming that it can't sell a pizza to someone based on how the pizza will be used. All that matters is that one party has money and wants pizza and the other has pizza and wants money. To suggest that the way the pizza will be used makes a substantive difference in the calculus is just... well, stupid.
Of course, that's not to say that the pizza owner should be compelled to do business with anyone. If you had bothered to read any of my posts on here, you'd know I'm a libertarian and I do not want anyone acting against their own judgement. For that reason, I believe that laws against discrimination are immoral: if someone wants to discriminate, he should be allowed to.
So the pizza owner should, in fact, be able to refuse to sell pizza to anyone for any reason whatsoever or even for no reason at all. That I find his reasoning stupid or crazy or whatever isn't relevant, except as something for me to take into account when I go shopping for pizza.
What's next, forcing black-owned businesses to cater Klan rallies with nooses around the necks of black figurines?
Are you sure you don't have me confused with someone else?
Or, Christian bakeries forced to make cakes with sex toys for adult film festivals?
Again, I think you're confused. You may want to lay off the gay sex for a while and have a cake or two.