Reiterating
my comment from c18:
If Zealark remembers everything from each loop until the moment of his death, just like Albus, then he's genuinely dangerous for Albus in a way nothing else is. After all, if your memories regress, it doesn't particularly matter if you're the one casting the regression spell or not. Keeping his memories would make Zealark almost as much of a regressor as Albus, and thus a threat on even footing.
All that said, Zealark is correct that Albus needs "stimulation". Because regressors have two main weaknesses (as the webnovel Infinite Regressor constantly emphasizes) which pose a genuine danger to them: other regressors, and their own mental health.