Looks like you may be right, OP.
https://www.southwest.com/promise/ says through Oct 31, while wayback machine archives all say through at least Oct31
BOO Southwest for the Halloween trick.
Until the risk of Covid is over, de-densifying the flight makes sense. HEPA filters don't run while boarding, and who in their right mind wants to be touching shoulders or fighting over a middle armrest with a presumed Covid positive stranger.
Look at Canada's
list of numerous recent domestic and international flights that have had confirmed covid infections. 44 domestic and 38 international flights within past 14 days. What multiplier of Canada's covid infections does the US have?
IMHO this move might tell the public to just stay home Nov 1st onward.