> It's just bizarre that the terms of the extradition treaty, which explicitly bars extradition for political offenses, would be irrelevant.

Basic UK constitutional law: judges apply the law as written by Parliament, not the law as it ought to be written if the treaty had been properly implemented. If this leads to the UK not following their obligations, the remedy for this is Parliament need to modify primary legislation to satisfy their international obligations. All treaties need ratification by Parliament.

(There are two major exceptions to this: the European Convention of Human Rights which was "domesticated" by the Human Rights Act 1998, and EU law which, pre-Brexit, was brought into UK law by the European Communities Act, and has now been integrated into UK law through the EU Withdrawal Act.)