www.makemkv.com

Hello -- Norton 360 just flagged this file having a problem -- is this a false positive?

Most likely.

Norton is still sold?!?

It got flagged for me too.
P.S. ~ Yes; Norton is still sold, and it works great.

Ditto. I sent it to Norton too as it was "Suspicious.Cloud.9"...

The comment about being sold was related to the quality of NAV, or whatever they're calling it now. I was a fan of it until it became such a bloated mess, which was about 10 years ago. When it started trashing my customer's computers more thoroughly than the programs it was supposed to stop, we changed vendors.

Of course, what we replaced it with eventually became as bad, and we changed vendors AGAIN...

Well, an official response would be nice.
I've had no reply from MakeMKV and I'm awaiting word from Norton as I've uploaded the 'quarantined' file.

Assuming you got the file from the official MakeMKV download site, you might want to consider this unofficial data point:

AVG finds no problems with any of the files, including uninst.exe.

Why not upload the file to virustotal.com and see if any other virus scanners detect anything.