What he's done is not being critized. It's a hell of a thing for sure! What is being critized is the click-bait crap of saying that he "beat the game", which is absolute moose-muffins!! The game crashed, and after reaching a certain point, it will do so randomly. That is NOT victory, it's just reaching the point where the game crashes. No one can avoid it, not even AI machine players. It's a hard-code limitation of the game and NES hardware.
The game designers NEVER expected, envisioned or believed getting so far into the game like that was possible, so they never coded a proper routine to handle the game pushing beyond the limits of the machine. Had they expected it, they would have coded in instructions for the system to handle things better.