Paul appeals to the law in 1 Corinthians 9:8-11 as a direct counterexample

In 1 Corinthians 9:8-11, Paul quotes 'you shall not muzzle an ox when it treads out the grain' (Deuteronomy 25:4) and applies this principle to argue that ministers deserve financial support. Paul explicitly says 'does not the law say the same?' and then applies it to Christian church practice. The letter of the law is about oxen, but Paul derives a principle about paying ministers. This directly refutes the claim Paul would never appeal to the law for church discipline.