Well, I'll actually address his claims instead of stirring up suspense now.
The minigun takes about a second to actually fire, and even during the spooling, the heavy can only move at 27% speed. It's a hitscan weapon, so even though technically you can get hit instantly at any range, unless you're within a few character models of the heavy shooting you, it's not going to deal lethal damage. At long ranges, a bullet is more likely to miss than hit because of the random distribution in the large firing cone. Whenever the heavy isn't leveraging his minigun, he can move at 77% speed. His only mobile damage is the shotgun, which 3 other classes have, and his fists, which is entirely unreliable because of the heavy's movement speed.
His massive hitbox makes him very easy to hit, and that compounded by his poor mobility, gives him the worst survivability in the game. The reason you see me with a medic 99% of the time is because going solo as heavy is suicide. He's simply too large and too slow. Now consider how easy it is to damage a heavy because of his speed and hitbox, on top of the fact that he has very bad range.
The obvious solution is to quit charging heavies like a dumbass. Don't expect to walk up to an overhealed heavy and live. Just keep your distance and stay out of the open. He's not going to be able to quickly change position or move in and out of cover like you can.
TLDR: The heavy is probably the second- or third-worst class in the game. You're just getting out-played.
