On the one hand, I see what you mean.

On the other, I didn't at any point say anything that wasn't true and it's not my responsibility to patiently teach them how not to be a short-sighted sycophant. Even if I wanted to, that would almost certainly not be possible for me to do during the course of one written conversation

I'm rightfully fed up with condescending idiots pretending that a lack of principles equals great maturity and shaming them is the closest thing to achieving something constructive when dealing with avoved anti-idealist cynics like this one.

Entrenched anti-idealist tribalists can't be reasoned with, but vehemently pointing out how idiotic their perspective is might jolt someone tempted to adopt a similar attitude awake.