I am not Ulti, and even if my weekly commutes could allow me to be Ulti if I chose AF over other carriers, it's not really motivating me to do so!
I am very surprised that, during these times of pandemic where travel is a struggle, and when you need to attract back your best customers, staff is not motivated by their management to cherish ULTIs.
If there is a seat available in J upon boarding, it would be absolutely normal to seat any ULTI member there. And that does not need to be a written or guaranteed benefit, but could be mentioned to all pursers during their training.