Review-bombing on this scale only happens to games that displease their actual audience. Leaks for The Last of Us Part II have been floating around for about a month and many fans of the first game didn't like what they saw and read. Physical copies of the game have been available since three days before official release date, so it's very much possible that fans who got an early copy had completed the game by the time user scores went live on Metacritic. The hate for this game isn't coming exclusively from people who didn't play it and have no intention of not playing it.
Review-bombing is not going to destroy the game or harm Naughty Dog. All the actual damage, if any, that can result for Naughty Dog will have been done by Naughty Dog themselves.
Your comment that fans of other console brands should be allies with PS fans rings hollow. After all, it is PS fans who find themselves in conflict with other camps all the time because they go out of their way to bash other gaming platforms while the other camps have nowhere near the same level of tension between them. That's why despite no buddy-buddy feelings between Nintendo, Xbox and PC gamers, it's very commonly perceived by PS fans that everyone else is teaming up against them.