Personally, I don't believe LeBron's a traitor or see anything wrong with him leaving, but the contract extension isn't really a strong argument to say why he isn't.
Almost any rookie worth keeping is going to get that extension after 4 years. As far as I know, most rookie contracts would enable a team to extend that player after 4 years and if the player doesn't sign, he's a "restricted" free agent. So, there's a catch-22.
After 4 years, a #1 overall pick like LeBron has made about $18 million, which is nothing to laugh about. But we've also seen players like Antoine Walker and Kenny Anderson who had made much more than that and were broke a few years later. So, that first extension is huge. For LeBron, it was about $43-44 million. Of course LeBron is going to sign that extension. That leaves not only himself set for the rest of his life, but probably 2 generations of his family after he's gone. That's why almost all good high lottery pick rookies are going to sign that extension. If they don't, they could sign somewhere else, but if they're restricted, the original team can match anyway.
I don't think LeBron's a traitor either way, but not sure using his extension as an example to prove otherwise carries much weight.