After watching his video again and my own, I am certain the adapter I made to make the Genesis controller work with those Master System games is exactly what would be needed if one has a fear of the Commodore 64 and that controller.
And there are other ways to go about that as well. If you've got a bunch of Genesis controllers and don't mind sacrificing its ability to work on the actual Genesis, you can open it up and cut the grey wire, which is the "select" button. You can install a toggle swtich on the controller itself to switch between modes. I thought about that but decided it would look ugly. Or, in my own unique solution which was 100% all me, you can rig up an adapter to bypass the wire that causes the issues all together.
This, of course, has no issues on the actual topic at hand, which is does the controller work with the Amiga. It absolutely works with the Amiga with no concerns. If there are any conflicting stories on the Amiga, it's from people that are confusing the stories involving the C64. But again, "if" you are tempted to say it can't be done on the 64, you are wrong, 1000% wrong. At best, those that say that are lazy, but more than likely they are simply taking stories they've heard, and some may even have some facts on their side, but they never ask the simple question of "how can I make it work?" and that is a fatal flaw.
If you're not going to be bothered to watch my video, here's a clip at the end where I have some words of wisdom for the people that think some things are not possible... When someone on the internet tells you to give up, that it's just not possible, 9 times out of 10, it most certainly is, they're just lazy.