Not sure why wanting players to play within the rules of the game makes somebody a jerk, but there you have it.
The background is that the players committee (elected by the players) have requested that umpires are more consistent in enforcing that rule and they haven't. Pascal Maria maybe, but every few of the others.
The rule at majors is 20 seconds. Federer has agreed that common sense should prevail after a long rally (i.e. allowing some flexibility), but obviously under most circumstances players should be averaging under 20.