Many years ago, UA tried to pull this stunt on me. I sent a nice letter, can't recall to whom exactly, pointing out that I flew UA all the time, I trusted them with my bag, they lost it, I told them in a timely fashion and listed many distinguishing items in the bag so they could ID it if name tags were gone. I said they admit they lost my bag, they should do what is right and pay me per their reimbursement policies. They did.
But that was long ago when UA really cared about their elites. And I'd never trust them again with the "just wait a while to see if we can find it" nonsense.