Assuming we're talking about performing this transaction in a jurisdiction where prostitution is legal, how is it any different from any other business transaction? I don't think anyone is particularly mad about payment processors refusing to process illegal transactions, it's the refusal to process legal but morally controversial transactions that is problematic.

I am mad about payment processors censoring transactions. they displace neutral forms of money like cash or cryptocurrency

Why is it problematic? Maybe they don't want to be associated with those things or involved in them?