Valuing “good” art is a moral stance. It’s a judgment of what human behavior is good or bad.

It's moral stance if you define good as moral. In other words, your reasoning is a circular reference, and not very useful

Different definitions of the word good here. Someone who thinks “good” art should should be destroyed is making a moral judgement in the same way someone who thinks it should be preserved.

It’s defining something as positive or negative which makes this a moral judgement not the specific value assigned.

I use positive/negative here because someone may believe there’s an incorrect solution to a math problem without judging such errors in terms of morality.

I don’t think that word means what you think it means in the context it’s being used. In this case a moral judgment simply means with respect to ethics. One could morally judge something to be good, bad, or neutral.