“There’s nothing in the rulebook that says an elephant can’t play.”
There are limitations on the size of the pads and gloves and jerseys a goalkeeper would wear.
An 800 lb man wouldn’t be able to fit in the equipment required unless he got a waiver from the league. And it’s likely the league wouldn’t give a waiver.
This would also apply to a moose or elk or elephant.
Dude plays a mean electric guitar.