Unfortunately, due to the fact that he is currently rotting, he is not in any position to move in thick, septic liquid or fast-moving current. Thus it would break him, or worse yet, dissolve him.
Since Simon is already rotting, as noted above, the curse effectively makes him some sort of undead that has a chance of very permanently dying if the curse isn't lifted from his wounds in the first game. Maybe it's just strangely forgiving difficulty for the rest of the bullshit in the game, but every time Simon dies, his next life / continue has him right where he was last before he died. Maybe he's effectively getting temporarily knocked out or only briefly killed, but since it's not the curse doing him in he gets right back up shortly afterwards with little consequence (besides losing all your hearts on a Game Over).
