What is believed to be wrong with his sentencing?
He didn’t get the death penalty. That’s what was wrong with his sentencing.
“What is believed to be wrong with his sentencing?”
He never saw a trial, and his lawyers never really got the full files. So there is a believe the sentencing was mishandled to cover some behinds.
Either way - his sentence is disproportionate to others who committed similar or worse crimes. If he was sentenced fairly, compared to spies working for actual enemy states, he would be free.