Why can't he be put in the same category?
Snooker is a dying sport. It is desperate for people to embrace it so much, that it even changes the game itself. The boring bastards who are the governing bodies are the ones who killed it, with their snooty traditions and outdated approach.
For years, it was all about keeping the top earners happy, and ensuring they remained at the top. They opened the doors, took everybody's cash, and then closed them again, in terms of qualification etc. The game needs personalities like O'sullivan. It needs it's bit of scandal more than it needs talent. Nobody cares if anybody knocks a 147 in anymore. It's too easy now, as players are so good. They care more about controversy, and rebellion.
As for players 'going about their business quietly', there have been plenty of players over the years who've rocked the boat one way or another, from drug taking, to common assault, to match fixing etc etc, including the Scotsman you couldn't recall.
O'sullivan won't be the first guy to hang up his cue, but he'll be the first guy that was miles better than the rest, but no longer wanted it.