If the choice is banning every fully evolved mon with Last Respects, or banning Last Respects itself, the move is gone.Yeah, I don't think there's any way either Basculegion will stay out of Ubers if they have Last Respects. If they're not preemptively banned, they're almost certainly going to get quickbanned in mere days.
I maintain that the real candidate for Last Respects potentially remaining unbanned will be White-Striped Basculin, the pre-evolution. (Assuming Serebii is correct in saying it gets the move, anyway.)
It lacks Swift Swim, is much more fragile, and doesn't have Ghost STAB without Tera. It might still be Ubers-worthy(which would probably result in Last Respects being banned, yeah), but I can also imagine it remaining in OU or even briefly terrorizing UU before being banned to UUBL.