We dont have anything to play for now so IMO its the opposite and now would be a perfect time if we have the right man lined up. Get a few nothing games under his belt, gets to know the players etc and will be more settled to start next season.
If the new man(ager) took charge of the last two games, he would need to win them convincingly. Let's say he lost them both, not much confidence going into the new season from the fans. Best to start a fresh, then there's no excuses, and he can really get to know the players in a pre-season. Pretty much a luxury to have a pre-season for a new manager of Newcastle United Sport Club, tbh.