So this makes the large majority of the story make sense. Rossy hates Bushi, was planning to start up a new promotion and was already beginning to woo talent over while still employed at Stardom.
Tony's reaction seems off because Bushi could have overruled Rossy at any point if he was blocking Stardom and AEW from doing shows together.
Or maybe he just bought into those rumors that Rossy was somehow funneling talent to WWE even if it seems those are unfounded. Might feel it's his fault Giulia allegedly already made up her mind on where she is going state side. Idk.