If someone doesn't want to discuss a topic, all they have to do is not discuss the topic.
Expressing such a position isn't a legitimate contribution to public discourse; it's a tactic that inhibits the process of building mutual understanding through discourse.
A reply that says "this is obviously wrong" may seem contentless but it's just "minimal content". You should be able to respond like this for the same reason you should be able to down vote things without comment. It's like a professor giving comment on an exam. Some questions they will just mark wrong, some they might write "makes no sense" to get the person thinking or clarifying and others they'd go into detail with.
There was literally zero argument in the original post. You don't have to write a full analysis of everything that was said, you can just pick the parts you're willing to discuss and focus your attention on that or don't engage at all.
It's not a way of engaging in dialectic/dialogue. It's saying it's so bad you won't engage in dialogue. That's a legitimate position in some circumstances.
That this is a court decision, however, might mean that in these circumstance one does need to directly challenge despite it's qualities.