Tosh you are using a sledge hammer to crack a nut.
1) Morals are not conceptual and therefore do not require an appreciation of conceptuality to be understood/ comprehended or even adhered to.
2)However, this is not a moral issue, tax evasion through the payment of cash is a crime - this has its basis in fact, regardless of whether the cash is subsequently used to help more people worship the baby Jesus or feed the worlds hungry.
If in doubt ask on an issue of morality just ask your self, "how are the jury going to view this.......?"