Either there's a rule of law or there's not. You can't hide from the police and then claim that the very act of hiding is an act of torture enacted on you by the police.
Also, as far as I'm aware, Assange didn't claim he was tortured, the UN experts on torture came to that conclusion.
It's about the people in power following a standardised process based on the crime that was supposedly committed, and being applied uniformly, vs the "rule of man" where things are handled on an adhoc manner based on who's in power and who's being charged.
The system can be breaching the "rule of law", not the individuals targeted by that system.
The idea that having to flee charges is tantamount to being tortured implies the state does not have that right. If there is to be the rule of law, the state has not only the right but the obligation.