It seems you are paranoid. First of all, he was the one who requested that the autopsy be done. Considering the courts granted him the rights to have Terri cremated instead of buried in Florida where her parents wanted her, if he thought any signs of physical abuse would show up in the autopsy he would have rushed the process of her being cremated right after she passed away, which isn't the case.
There is absolutely no comparison between Scott Peterson and Michael Schiavo. (Although some would call them both murderers, which in fact, is debatable and matter of opinion.) The autopsy will reveal all it's findings but was primarily requested by Michael Schiavo to show and prove the extent of Terri's brain damage.