Lux Flyer

*Which is effectively waived automatically under no change fees since you can cancel, receiving the full FFC and then immediately rebook, retaining the balance as a residual. The $50 refare penalty was really a thing when there were change fees, and while it technically exists still, no one would process a refare that way while change fees are $0.

Regarding the original question of holding PZ. I think as has been alluded to here, technically no, you shouldn't be able to keep the PZ space, as that space would need to be released as part of the refare, and there is no guarantee RM automation would immediately put that back into inventory (especially if the flight is now J1). An experienced agent has the expertise/ability to force that space open and put you back into it, but again you're relying on them knowing how to do it, and doing you a favor to retain that space even though the system decided not to release the upgrade space. The question really becomes is saving the $80 worth the risk that you won't keep the upgrade?

Edit to also add: as far as I'm aware the refare to a cheaper fare for $50 penalty is not officially published publicly anywhere, and could have been eliminated. Again, with change fees currently at $0, it's a moot point, but there is nothing that says that policy hasn't been changed or eliminated.