Thought it was a pretty good episode, although Anarky teaming up with a couple of clueless vandals didn't exactly make him seem like the smartest or most formidable opponent for Batman. If he really wanted to create chaos, you'd think he could come up with some bigger and more effective ways to go about it.
I agree for the most part, but I think Anarky freed those two idiots to "undo" what Batman had just done. Each time Bats apprehended those two, Anarky immediately set them free and unleashed them with bigger and badder tools.
I don't think that Anarky really believed that Beavis and Butthead would pose an insurmountable threat to Batman or Gotham in general; it was just a clear message that "whatever you do, I can and will undo." An act of chaos in response to every act of order.
But I do agree that his manipulation of those two losers was a meager beginning in his larger "chess" game with Batman. The last part of the episode shows that threat escalation should prove to be part of his greater agenda in future episodes.