The definition of a political offence is not defined in the US-UK extradition document, leaving it open to interpretation. Historically, the definition of political offence has been defined under international law as crimes against the state, including espionage or treason.
Assange does not stand accused of any of these crimes. His charges are for conspiring the break into a computer. This does not count as a “political offence” in the historical, international legal definition of the term. Therefore, he is not exempt from extradition in this circumstance.
This is a provable crime. If the court finds evidence that he did conspire to break into a government computer, he will be found guilty. If there is no evidence or insufficient evidence of the crime, he will not.
The very narrow scope of the charges does not allow for any political agenda to bleed into the trial. The US government cannot add any further charges to his case. The US-UK extradition agreement states that only the charges filed in the indictment request can be brought against the prisoner.