It is very rare for an "Ask a Mentor" question to have such a simple and obvious answer, but this one is a no-brainer (and I very rarely, if ever, use this term as most questions are not obvious and have varying levels of complexity). But the answer to this question is: "NO"...with a capital N. And a capital O as well.
My colleagues (above) all provided excellent responses, and Michael Stratford beat me to the punch by mentioning the book, "The No A-hole Rule" which was, coincidentally, the very first thing I thought of upon reading this question.
The guy is toxic. And after everything it took to finally get rid of him after what you describe as "years" (!) of conflict and dysfunction, there is absolutely no reason in the entire world to let this guy back in to once again infect your company, its culture, and its people. It sends the wrong message to everyone else, and you've gotten along fine without him since. So just say "no thank you," get back to work, and don't give this guy a second thought.
In fact, the best thing for you and your company would be to LET (and even encourage) this guy go to a competitor! Let him sink THEIR ship!
There are so many good, smart, experienced, and passionate people out there looking for work. They may not have this guy's level of experience. But I would take a smart person with a positive attitude over a bad apple every single time.
There's a classic Harvard Business School case study called, "What a Star, What a Jerk" that deals with the difficult decision of what to do when your top performer is an ass. In that scenario, the hard part is deciding whether to keep him or let him go. But you've already made that decision, taken action, and moved on with your life! So congratulations...he's not your problema anymore.
So rejoice in that, move on without looking back, and sleep well in knowing that you made the right call.