FYI, arm wrestling is a test of technique moreso than strength. And IMO you are generally correct that people who actually work with their muscles tend to have more functional strength (endurance, efficiency, and versatility) than people who train in gyms and have very pretty muscles that aren't terrible efficient in demanding real world situations (lots of explosive strength but only optimized for very specific trained movements). Still, this has nothing to do with what type of protein one consumes.