I just want to second that the SWA policy is one of the best policies ever written. I actually bookmarked it.
Especially "encroachment", "extended" and "fluctuate"
Customers who traveled without full access to the seat purchased due to encroachment by a large seatmate whose body extended into the neighboring seat.
Because size can fluctuate, we are unable to give blanket authorization.
made me take my hat off to the writer