A system of "mass incarceration" should have no impact on any individual case. That's beyond stupid.
The judge interprets how the law applies to the specific facts of this case. The law says extradition is not allowed in some circumstances. Those circumstances include how the prisoner is likely to be treated, and the health of the prisoner. Some other extraditions are ok according to the law because those factors vary in each case.
https://www.legislation.gov.uk/ukpga/2003/41/section/91
There have been extraditions of other people charged with computer hacking offences like Lauri Love and Gary McKinnon where there was a similar concern. In both Love and McKinnon's cases, both were on the autistic spectrum.