A SOLUTION WAS FOUND! I was able to convince a service center to try changing the car's configuration (at a cost of a half hour labor charge) and once *I* had to suggest to them that they needed to change the configuration on the server rather than just in the car.... It worked! The seat menu in the computer is gone, but SO ARE THE ERRORS. The seats are plugged in and happy, and I can use them in full mechanical (which is smarter anyway). I don't know if the computer is still trying to set the locking / unlocking if I push the buttons (and I won't!) because I have the seat motors unplugged anyway. The errors are gone though, that's all I care about.
If I put a watermelon on the seat it still gets snotty about an unbelted person, so that works. Presumably the airbags will work if needed too. I don't think I'll test that though.