I mean, maybe he's firing them because they were the people behind the idea of pushing back the powerunit another year, when it could have been a beneficial one to do it in 2021? at least thats whats coming to mind for me. Especially when we remember that the engine apparently might not be as reliable as they would like.
Maybe Rossi is seeing that and severely criticizing them for taking the decision to postpone the engine so much when they could have used 2021 as basically a massive test session for the engine before next year, and clear out the engine gremlins before this season. I dont know, food for thought?
On a side note, did prost honestly contribute anything to Alpine and Renault? So worst case, isnt that just more budget for the team to improve?