I mean, 4 hours is way too long for a brisket unless you're cooking a tiny flat or doing something weird with the temp. Most people I know run 12 to 16 hours at 225 and the meat comes out fine, so the idea that 4 hours is some magic number doesn't add up. Maybe his uncle just got lucky with a small piece of meat and decent wrapping, that's not proof of anything. Nine years of "being right" could just mean nobody bothered to argue with him anymore.