he persist in complaining ... for months, we let him rant and rave

Disagreeing in part:

I agree with you that ranting and raving are inappropriate and that they should, if extreme enough, be grounds for dismissal. I agree that various people have ranted and raved, repeatedly.

I do not agree that I am among those ravers. My comments have been far milder than those leveled at me and others.
[Examples are readily available.]