I’ve known Mike personally for more than 30 years. He’s hardly a “shade tree mechanic”. He is an engineer and took to this study after a mutual friend showed him the staining and peeling paint from putting G100 in his aircraft.
Have you watched the videos? They are absolutely compelling. He shows his A/B comparisons with G100 and 100LL.
If you don’t believe the videos, get some G100 and duplicate what’s he’s done. If your findings are different, publish your own video rebutting his observations. All you need is a cell phone, avgas and a YouTube account.
Fly safe.