Seriously, you don't owe anyone your time to have a pointless debate. Boundaries are important, as is not wasting your own time. You explain the rules, you're done, conversation over.
The only thing will accomplish is demoralizing your team and having then turn in the bare minimum workong code. You clearly don't care about what your team thinks, so why should they care about going above and beyond when writing their code?
'I didnt ask you to do it, I'm telling you to do it. Are you going to do what I am telling you to do? I will take any answer other than an explicit confirmation as a 'no'.'
Do you find this type of answer to actually help you accomplish your and your organizations goals? I don’t think many people would react well to that type of military style order frankly.