One more piece of the fact puzzle; Jeb did not act simply under his executive authority to "pardon" as you stated it. The FL Legislature passed an emergency law to save Terri's life, and Jeb signed it. Then under that law, he acted to restore her feeding tube and rehydrate her. Schiavo and attorney challenged the constitutionality of the law under the FL Constitution, and the FL Supreme Court overturned the law by declaring it unconstitutional. Jeb appealed to the U.S. Supreme Court and was denied a hearing.
Apparently the office of governor of FL is a very weak one institutionally. This was also said of the TX governorship under George W. Bush.