Greer's hands aren't clean in all this. He apparently made a deal with the devil to get this done, thinking that this would slide through courtroom almost unnoticed by the public. Instead the eyes of the world are watching him.
He wants Terri dead. Why is it so important to him?
Firstly, because he's got a pro-death agenda. Evidence: 1) he made a deal with Felos before he even got "assigned" this case; 2) he used to be an attorney for Scientology; 3) he's in cahoots with all the players of/at hospice; 4) he's got money coming in, i.e., obvious from re-election from pro-death interest groups.
Secondly, it's gone way beyond the initial pro-death agenda. Evidence: 1) he's abused and broken numerous Florida laws and its constitution (see Empire Journal articles); 2) he's corrupted the rule of law and wants the "evidence" destroyed (cremated) before others have physical proof concerning her body; 3) he's been aiding and abetting the murder, and must see it through to the end because, to do otherwise, he fears an investigation into his own criminality.
I'm sure there's plenty of other reasons others can think of about why Greer wants Terri killed.
This popular monster first ordered Terri's death in 2000. He has taken five years to achieve his dream. The man is mad, and so are those Pinellas/Pasco voters who supported him. Greer is a staunch believer in raw judicial power -- particularly when he is exercising that power. FL people don't seem to understand that well, do they?