I flew WN for 19 years exclusively, RT every other week, 90% of the time I was connecting or through passengering.

I always heard "please do not change seats until we have a through count (which I promptly ignored if not already in the exit row (rare)).

I never heard you may NOT change seats or may not sit in the exit rows.

Only once did I hear an invitation to leave the plane as the next leg was going to be substantially delayed.

If it was 40 minutes or more until departure and I asked to leave & get food, it was always granted.

Note that I haven't flown since COVID or was I ever more than a handful of through passengers. If 50 people tried to leave at once, I bet the answer would different!