I'm trying to recall the Ricky Williams thing but (without looking it up), I thought he decided to leave/retire so he could do what he wants. That was his decision and I don't have a problem with that (again, if I'm remembering it right).
Gordon had made a promise to his team to be there. He signed a contract to play football and then willfully broke rules stipulated by that contract. The Browns were relying on him to fulfill his role in the offense and had spent time and effort putting in plans and that involve him being there. Even after the first suspension (or two), they likely expected him come back and play. Yet he has repeatedly failed them and, though I know he mentions that in his letter too, that he's "sorry he's letting them down," at some point, sorry isn't good enough.
He may in fact not be an addict, though his actions seemingly portray him as one. Regardless of what his motivations are in life, I'm judging him by his failure to fulfill his end of things regarding his team. I did assume he wanted to play football and wanted to make money. Those could be poor assumptions and may be incorrect entirely. But he agreed to play for the Browns and in return he was going to be very well compensated. He then made decisions with his life that, in the context of his job, are very poor and nearly indefensible.
Edit:
My favorite paragraph might be this one:
In connection with the DWI case, the league — in consideration of the fact that my blood-alcohol level was just .01 over the legal limit — agreed to shorten my punishment from four games lost to two. These games were tacked on to my eight-game suspension that had been levied on account of my inadvertently inhaling second-hand marijuana smoke last offseason.
Does it really matter how over the limit you are once you're over the limit? And just how much second hand pot smoke do you need to inhale in order to fail a drug test because, without being a biochemist, I'm going to guess it is lots and lots (if it's even possible). Comical indeed.