It works best if you don't reply immediately. I recommend successively increasing the response delay. Keep it short enough to make sure that they don't start bugging you on other channels, but long enough to make sure they have time to cool down and question if the continued effort is really worth it.

As long as the response delay increases at least geometrically, there is a finite bound to the amount of work required to deal with a pull request that you will never merge.

Why would it be acceptable for the sumbitter to behave this way and not the reviewer? We do have AI "assisted" submitters behaving exactly like this and acting irate when forced to actually reflect on the turd they're trying to shove into my inbox

If people do this to him? How else to react?

The context here is lots of vibe coded garbage thrown at the reviewer.