Actually, I missed this. He wasn't effectively pardoned. He was released as part of standard practice in Scottish law whereby terminally ill prisoners are allowed home to die. You're sounding like a Sun leader writer.
Apologies.
This case winds me up however. I really don't see why he couldn't see out his sentence as the rest of us would if found guilty of a similar crime. It strikes me as nuts and the most obvious 'plot for oil' since Powell submitted his evidence to the UN.