We can speculate on "how well" he was rehabbed. My wife is very close to the people who actually managed that process and this is what she got from them:
- It was clear that he was completely numb to the feelings of the animals and utterly surprised that people were so upset about this. It was as if he was a fish that learned that the entire world wasn't made of water; he was that ignorant and blind.
- He spent a lot of time with people who were providing him with a different way to think and feel about it, and with people and dogs who had healthy relationships.
Beyond that, the information was tightly controlled. It was clear that part of the agreement between him, the Humane Society, his agent and lawyers, and the courts was that the results of the rehab process would be private and not a topic of conversation.
So essentially, we'll never know.
The animal welfare field is still split about all this, similarly to the posts on this thread. Some can't ever forgive him and just want him locked up for decades. Others see the need for rehab and that his case can be useful on a larger scale. In reality, I suspect they all carry some of both positions.
There's also remaining question of how much of this is genetic (sociopathic, dominant aggressive behavior) and how much is cultural learning.
For our purposes, the fact that he was a Jet puts him in another category of human being altogether, so the above conversation is really secondary.