FoxyCryptid

I guess it depends on the context. If by "serve" you mean "servicing" the KKK in the sense that you're allowing them to burn a cross on someone's yard, then yes, morally/ethically that'd be unsound, but if by "serve" you mean servicing a member of the KKK who's say shopping in a store or getting something from a fast food joint, I don't really see the problem with that.

More like asking someone(a black baker, no less) to bake a cake celebrating their creation for a celebration.

Ahhhhhh, I gotcha, that is pretty asinine. Kinda like how those Christian bakers in Oregon were pretty much forced to close shop when they politely declined to bake a cake for a gay wedding. Again, not necessarily technically right, but seriously, it's not like the couple was prevented from just going to another baker, so it really wasn't that discriminatory, and to drive someone out of business over that is just asinine.