Bleak's statement doesn't appear to be directly related to the issue, unless he tried to manipulate something and broke mob generation code going back to Third Dawn for that subserver.
All appearances are that the shards with the broken west Ilshenar are just that - BROKEN. Not "shut down"; BROKEN. The shards affected are about the opposite one would expect for deliberate shutdowns - but are ones that, if the spawn numbers weren't kept down, because the spawn went unworked for a while, could have screwed up something over server maintenance if the existing code wasn't set up for it.
Hell, it almost sounds like the managed resources / biosphere that they originally meant for UO, where if X of something existed, it would stop spawning. Only there was a bit overflow, or something, to where the server code is trying to divide by zero or what should be a positive number in a formula has been turned negative. There's a reason, for example, piles are limited to 60,000, not 64k, and it's specifically to avoid that kind of bug, after it screwed many things up over a decade ago. And, don't forget where Smith BODs were screwed up for most of a decade because someone, somewhere, removed a closing parenthesis from the functioning code by accident, when tweaking it - it didn't STOP the code from working - it just made it have unintended results.