You really ought to read his (updated) Wikipedia article before you get all high and mighty. It would seem this guy has done some pretty impressive things to protect freedom over the last few decades...

Whether or not it is important to leave a job on good terms is a personal issue for you to answer, not a question for the community. It might make a difference in your future career but it is much more a question of personality, and whether you would regret the bad blood.

If you decide you do want to leave on good terms, best approach IMO is to talk to the nut directly, don't go behind his back or get anyone else to intervene on your behalf. Try to be the hurt pal, let him know how you want to be remembered as a good worker, that you were there a long time, that it bothers you he could think you were causing trouble, and so on. It might not work right away, or at all, but if so you'll know for sure there was nothing more you could do. You may have every right to be angry (we can't know for sure, but it seems you do) but acting angry does no good if what you want to accomplish is to calm down the paranoid.

And if it doesn't work, *then* calmly make sure you've covered all your bases: dot your i's and cross your t's, keep proof of everything, and don't say anything stupid.

In my own experience I've felt sometimes it was worth going the extra mile to make someone happy, and sometimes it wasn't.