Heck, there are some players with a GM title who barely reached 2500 for 1 or 2 minutes & then slipped back to their real average playing level. There should be a rating requirement that has a player keeping a 2500+ for a certain # of tournaments or # of games.
can be the GM title be achive even if your FIDE rating is 2400 or lower but high Tournament Performance Rating (TPR)?