People do not choose a sexual orientation, nor do they choose the color of their skin. Discrimination for natural factors is the antithesis of America. All men are created equal, common welfare, etc.
Believing in a rigged election is up to the whims of an individual. The same as how believing violence is an acceptable answer is the whims of the individual. Those are perfectly discriminatable factors, and rightfully so.
Also, for reference, legally yes a cake shop can choose to not make cakes for any reason.
My point here is not that Trump is a great guy and businesses should be forced to deal with him. Quite the contrary, if I had a business that interested him I would probably also like to refuse him service. But I am not a hypocrite, or I try not to be, so I do think the same freedom should apply to every business, for any reason, as opposed to everybody being forced to adopt the same morals as me.
Well, in the case that has been litigated to the Supreme Court, the answer was “Yes”, though in part that rested on specific behaviors by the state actors that tried to say “No”, and the outcome might be different otherwise.
But certainly, its not established as a matter of law that the answer is “No”, so resting a counterargument to the Shopify action on that being the answer is weak.
(Its also weak even if the answer was established to be “No”, because even if it was it would be because of specific laws protecting against private discrimination in public accommodations on the basis of sexual orientation, which are an exception to the general principal that private businesses can choose who to do, or not do, business with.)