Hendrick can say "Please" 1000 times. He will not get the shot because everybody knows that GSP vs Silva and GSP vs Diaz will give much more money to Dana.
As for Diaz's not being impressed. Well, GSP did a great job against somebody who defeated Nick. And Nick normally has troubles against wrestlers, I do not think he would beat one of the best wrestlers in MMA.
Also GSP yesterday showed that he can defend submissions. Carlos attempted a lot of them and no one was even close of putting GSP in danger. Of course Nick has better BJJ than Condit, but still, GSP is just a machine in WW.