Wrong....he can pardon or grant clemency to anyone he chooses.
Well, I’m not a criminal lawyer and I graduated from law school 25 years ago, but I’m pretty sure the law remains the same.
Article II, Section 2 of the U.S. Constitution states as follows:
The President…shall have the power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.
Unless there is something about the Mumia case I don’t remember, he committed a murder, a crime against Pennsylvania, not a crime against the U.S.