Yes, but if you ignore his jabs, then he looks like a cocksmock, whereas if you respond, you both look like cocksmocks.
I mean, just think of old Dominus Nox jabbing at me. How often do I respond? And what's my image here compared to his? Sure, vile racism and batshit crazy politics is most of it, but him zapping at me while I don't respond at all helps a lot. He makes himself look bad, and me look better.
You should do the same with RPGPundit. Plus, you know, he has so many people jabbing at him, old Nisarg, that if you stop he'll soon forget you and move on to new targets.