What does hamlet mean when he says' "ay, sir, that soaks up the king's countenance, his rewards, his authorities. but such officers do the king best service in the end. he keeps them, like an ape, in the corner of his jaw, first mouthed, to be last swallowed?

Basically he takes advantage of their hospitality and lure them with kinsmenship, but as they are luring in the main 'course' - slowly but surely they are destroying the things around them. finally whenever they prey is manipulated and that there is nothing left to destroy - they strike and kill with no remorse.