If Chaos is starting to move, it might be because they expected the previous Everchosen and Great War to have knocked out the Dwarfs completely.
The Great War Against Chaos saw the end of the Norscan Dwarfs, and the loss of enough Old Holds to put the Throne of Power's energy supply into the negatives. That meant that it turned the lifespan of the Dwarfs into a numbered one; as soon as the power ran out, they would be screwed; every Karak would have to close their doors and live deep underground, and every surface-dwelling Dwarf would start to petrify.
At the same time, the Great War was also meant to disrupt and massively damage Kislev, the Empire, and as many other Old World nations as they feasibly could. To be the death-toll of the Empire which was in the middle of a civil war that had lasted for a thousand years. What could go wrong? They probably did not expect the Gods of the Empire to send signs and tell everyone to cut that shit out and to prepare for war and to rally behind Magnus, and for Magnus to manage to beat the Everchosen.
And now, the Dwarfs have reclaimed two Karaks and have gotten their energy flow into the positives. What was supposed to be a knockdown blow for the Karaz Ankor, and a bitter "stolen hope" as their new leader reconnected to the Norscan Dwarfs only to lose them and gained the throne only to find out how close they are to defeat and death, turned out to not be a deathblow; and instead the Karaz Ankor can continue on still. The Empire wasn't destroyed at all. Kislev... well, it's not fully recovered a century and a half afterward so, well, yeah.
As for the Alric thing... Honestly, has anyone considered the possibility that he might have a point, or thinks he has a point? Namely, what if he suspects Mira and/or Egrimm of being trouble and bad news? Therefore, he might think that he has to regain and maintain power; and also keep an eye on his apprentice, in case he falls or has fallen all along or whatever. I mean, if his suspicions were right and Egrimm were a secret Chaos cultist or he had heard a prophecy that he was destined to cause a great disaster or something... yeah. (Or maybe the prophecy was more vague, something like "one of your students/creations/pupils/seeds will cause calamity" that could be interpreted to refer to your apprentice or to your children or to butterfly effects of your actions. You'd curse and grumble and second-guess yourself, but you'd keep your apprentice on a short leash anyway, wouldn't you?)
Things probably seem reasonable or logical to the people making those decisions or in those mindsets.
... Also, we don't actually have all that much information on Alric, Mira, and the Light College. We just have Egrimm's grumblings and complaints and 'We know Alric's gone here and here and there' and the rest is speculation.