chess players need strong egos as we absorb many losses. The more we play, the more we know losing will be a real possibility.
That said, yes "sore loser nonsense is less of an issue with stronger players." Though you will see some refuse to shake hands and absolutely hate the other person. Read about Korchnoi playing Petrosian matches -- as those top notch players complain about each other shaking the Table. Also Korchnoi matches with Karpov as Korchnoi's family was being held hostage.
Just wondering if sore loser nonsense is less of an issue with stronger players. Do masters send insulting messages to each other or refuse to resign in a lost position, just letting their clock run out to punish the other player?