Very true. Bwatu is an exceptional tactician and would be a good match for Thrawn. However, I don't think the simulator had every detail on Thrawn's thinking. If they worked with Palleon, then yes they would. But even Palleon didn't know all about Thrawn's thinking process.
I think beating the simulator makes him a good tactician either way. It may not be the real deal but it is close enough for him to be a good challenge imo.