There isn't anything political nor artistic about his performances. He is obviously a junkie who lost his mind a while ago and is long overdue for extensive treatment.
To be fair, you need to have a solid grasp of the Russian history, society, and culture to understand Petr Pavlensky's art and its relevance.
For instance, there is a Russian parable about a dog sitting on an iron nail. Although the dog whimpers from pain, it sits and sits and sits on the nail forever. The lesson of this parable is that the dog is hurting enough to howl from the pain, but not enough to get up and move.
When Petr nailed his scrotum to the Red Square, it was a modified allusion to the dog parable: the Russian people as a whole sitting on a nail but being unwilling to get up. However, his act symbolizes not just the unwillingness of the Russian people to rise up, but also the fact that in many ways they are simply unable to do so because the iron fist of the state shatters any attempt of opposition or political movement.
Additionally, he created a precedent where the police and the passersby did not know how to react and what to do, effectively putting everyone is a state of confusion and social stupor. The shock factor elucidated the empathy or lack thereof from the Russian people, therefore exposing the national mentality of indifference and anger.
And when they put him in the psychiatric institution? I am sure he expected that and in fact wanted to be put there. Why? Because in USSR dissidents were always sent away to Siberia or put in mental institutions to be drugged to the point where their consciousness suffered and their political activism vanished. It was done with the simple goal of neutralizing any organized movement by the people, and when the modern Russian government puts a political dissident in a mental asylum, they effectively re-enact the Soviet methods of dealing with "enemies of the state." Again, Petr exposes the horrifying crimes of the Russian state with his acts.
Although quite extreme, Petr Pavlensky's genius continues to inspire intellectuals and activists in Russia and abroad.