Maybe they’re telling the truth and they already killed them all.
It's a good idea to call them out -- either they don't have any authority over the various criminal gangs that make up Hamas and every other part of the PLO, in which case negotiations are pointless and NOT in good faith, orrrr, they need to produce them toot sweet, orrrr, they all get leveled and booted from Gaza. Having no authority means they are living high on the hog from stolen aid and whatnot without actually being in charge of anything.