KG was about an 18 time All-Star, a former MVP, a former DPOTY and has a champtionship ring. There is noboyd in the league who is above him - he has earned the right to stand on the same level as anybody else in the league, and to be a crazy, insane, intimidating freak.
Stephenson is young, he's earned little personal or team success so far in his career, and aside from one good season he has little to boast about.
Also KG's antics were usually driven by his competitiveness and desire to win. Most of those actions were either emotional reactions to a big play, rections to opponent actions, or moves mintended to put a player off their shot, etc.
Stephenson blowing in Lebron's ear is something entirely uncalled for. You don't blow in somebody's ear because you are on an adrenaline trip, or to put them off their shot (I don't believe Lebron as shooting at the time). That falls squarely in to the JR Smith / Metta World Peace / Delonte West world of pointless childish antics. Especially when the person he's doing it to is a multi-time MVP, championship winner and arguably the best player in the world. There is a certain degree of respect that a insignificant teenage dirtbag like Stephenson owes a player like Lebron. Until you have won some MVP's, won some titles or at least made some All-NBA teams, you need to sit down and shut up.
Likewise KG also kept his antics on the court. When he was off the court he always spoke respectfully towards other teams, other players. I don't know if I've ever heard KG disrespect an opposing star (or team) in the media. Stephenson's words about Wade's injuries simply make him look like a childish moron, especially since Wade is 3x the player Stephenson probably ever will be, has 3x as many champtionships as Stephenson will ever have, and happenes to have just knocked Stephenson's team out of the playoffs...for the second straight season.
Many people outside of Celtics hate KG for his on court antics, but I don't think anybody woth anything has ever criticised KG as a teammate for his lack of focus. Likewise as much as KG will ALWAYS hate every opponent he plays against, he will also always respect them. KG never takes an opponent for granted - he plays with the same passion agaisnt the worst team in the league as he does against the best team. I respect the hell out of that.