Lot's of input!
I think the issue of possibly falling off the tractor is a non issue if you wear your seat belt, so those concerns pretty much go away with seat belt use.
Can see the advantage of the tractor turning off if tipped on its side, due to the seat switch causing shutdown. Not sure if the seat switch would activate if one is wearing the seat belt, but it might.
Looks to me like a tilt switch would be a better option, in the case of tipping or rolling. It would cut power regardless if one was wearing a seat belt or not.
I am having trouble with the fish on Friday analogy.

This is even having after gone to Catholic grade school (over sixty years ago). Could be because I am from Pittsburgh...:laughing:
By the way, I think having a mower that turns the engine off, if you back up with the mower deck engaged, is worse that a seat switch!