The mod isn't banning people for debating in the comments. A lot of people the mod is banning (myself included) are people who only downvoted posts. Considering that a large portion of the posts are blatantly antagonist things like this, it easy to see why they're getting downvoted. If you're going to insult 90% of the users on an instance, then you're going to get downvoted.

The mod could have made the community private so they could insult people without consequences, but instead, they decided to remain public while banning anyone who downvotes their insults. They want to continue to antagonize the instance while removing the instance'a ability to respond. They want to artificially lower the number of downvotes they get, so it doesn't look like their antagonistic bullshit is as unpopular as it is.

Everyone could block the community, and if you choose to do that, that's a reasonable response, but it shouldn't be the only response. We should be able to express our opinion about the content in our feeds, even if it's just downvoting it. Why should an entire instance be expected to hide from one abusive community?