I suppose the only safe thing would be to seat big people the farthest from the exit rows as possible. That is the only way we can be sure that they do not block the exits for anyone.

OTOH, perhaps the exit doors should be configured to allow anyone of 300 lbs or less to exit quickly. Does any standard for size of exit exist?

Frankly, when all is said and done, I figure that the chances of being saved by being able to exit via one of these doors is slim or none.