Vasseur does not have the final say in this like you are pretending he does. The person that employ Fred does. Just like Zak Brown has veto power of Stella. It could also be a personal decision not to move to Italy, the nuances of the situation are still not known, so stop slating Ferrari and Fred as if you have the process documentation.
Let's also not pretend that the 2026 regs aren't shaping to be an engine reg cycle, at least for the first couple of years, something Newey will absolutely have no control over.