FA's don't stay in the immediate area of their jumpseat for the whole flight. This point aside, I agree with Fangs' original point that "safety" matters when blocking non-revs from those seats, but stops mattering when they can sell them.

But this seat blockage thing applies only to A321?
Other jets ok?

Good point and I honestly don't know. I think we're in agreement on Fangs' point that the company isn't applying it with actual safety in mind if they'll throw it out the window when they can make money. It doesn't make sense and I don't know what the actual intent is.

EU depends on tourism. They are cutting off their nose to spite their face. Our economy is on fire.

From what limited info I've read on the subject, the problem is the lack of available JS near the aft galley on the 321. When FAs are up working in the galley, they don't have access to a seat if needed, therefore the last row was blocked for use as a JS.

It has to do with available jumpseats in the galley. I believe the 321 has 2 in the aft so if 3 FAs are back there they don’t all have a seat to get in during turbulence. Now they have one as long as it’s only nonrevs that wanted to sit in the last row. There are (or were, prior to COVID) a few other aircraft that had the limitation placed on them too. I don’t remember what they are and my iPad has too much UNA dust built up on it for me to check.