Understood. It is fair. I agree a better choice long-term would have been to have him presumed dead or a prolonged coma. Writers overuse deaths that can't be reversed; they are so short-sighted sometimes. But considering how many long-term characters ended up written out carelessly afterwards, I think all things considered they got good story out of his exit.
I am pretty certain he wasn't fired. The story I had had always heard - and I am not putting my own credibility on the line for it but I heard it often enough including on here - was that he was thinking of leaving for a variety of reasons but got really pissed off when Christine Tucci, who he was dating at the time, got fired and that sealed the deal and he decided to walk.
As for his soon-afterwards temporary return, he wouldn't be the first guy to make an important decision on an impulse and once faced with the phone not ringing and the bills coming due, be a bit "Oh s**t" about it.