I wouldn't exactly call Perm or Mordovia "remote". Both are well within "European Russia", and Perm's a million large city and administrative capital. I strongly suspect that was put in to evoke the Gulag system and internal exile in Siberia...despite the fact Perm was part of the Gulag system when it was a major industrial centre, much more populated than it is now. Hooray for historical inaccuracy being used to fuel modern day inaccuracy.*
The rest of the article is pretty accurate. Life in the prison camps is rough, Soviet-style and while physical torture has never been reported, solitary confinement for minor infractions, minimal food, communal housing, lack of heating and sleep deprivation are the order of the day.
*To be honest, it would take a miracle for a Guardian article to not contain an inaccuracy about Russia. They do employ Luke Harding and Miriam Elder, after all.