why does hamlet not cooperate with rosencrantz and guildenstren?

Hamlet knows his two buddies were sent for to spy on him. They have never been totally honest with Hamlet so Hamlet replies to them with riddles and more questions. He calls them a sponge,

"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. When he needs what you have gleaned, it is but squeezing you and, sponge, you shall be dry again."

He means that they soak up information for the KIng and then the King squeezes the information out. Then he sends them back for more.