I think even for a dumbass like Ozzel or Hux, keeping tabs on Ezra would be considered a tactical necessity. But this is especially the case since we're talking about Thrawn, the *ultimate* strategist and tactician. I struggle to understand how that's not considered a given.
It's clear that Thrawn had been planning an escape for a long time. He was also coordinating his escape with the aid of witches using magic powers. Ezra has the Force, and can therefore be considered capable of perhaps sensing these witches and their dark arts. The same Ezra who had already proven capable of single-handedly disrupting Thrawn's plans and thwarting his best efforts.
You say that there was nothing to sabotage until the Eye of Sion showed up, but that completely ignores the extensive repairs being made to the Chimeara for what likely took years. Why would Thrawn think that Ezra would be unconcerned about that? Why would Ezra not view the repairs as part of some way that the genius Thrawn had devised to get back? Sabatoge *at any point* of this process should've been on the table as at least a concern, no?
Even your point about Sabine proves why Ezra would be considered a potential asset, if nothing else. Baylan convinced her to risk the entire galaxy for a chance to reunite with Ezra. Why wouldn't Thrawn think himself capable of coming up with a way to manipulate Ezra's emotions to call on space whales for a return trip home? They routinely migrate there (to die - which is a unique spin on the purpose of migration
), so it's not like there'd be no potential opportunity.
We're talking about a uniquely resourceful, Force-powered Ezra - who had shown willingness to sacrifice everything in order to stop Thrawn once before. Might be a good idea for a supposedly brilliant and desperate man to not lose track of an adversary like that. But you seem to disagree, and that's fine. Just wanted to make sure I'm clear on what we're specifically disagreeing about and why. I believe Thrawn needs to be written much more carefully and capably than any other SW antagonist, otherwise his defining traits get compromised.