When completing a merge, if the two LNABs are the same, that is the result.
If they're different, you get to choose which to keep. And you also get the option of rejecting both and choosing a new one. This creates a new profile and merges both of the others into it.
(In passing, it would be good to have the LNAB change option when they're both the same, because there are many cases where they're both wrong - mainly because Ancestral File doesn't conform to WikiTree formatting regulations.)
But when you choose the "new LNAB" option, you then get told you can't, only a PM can do that.
So we now have this situation where a pending merge is sitting in the queue, fully approved (if only by default) and waiting for completion, and anybody can jump in and do it wrong, but only a PM is allowed to do it right.