One possible explanation is that Putin wants to prevent a possible rival from winning over oligarchs by promising to make agreement with the eu. Many oligarchs are losing a lot of money on this war and it is likely that a coup that replaces him with a more friendly leader could ease up the sanctions. Without the gas leverage this option is less likely. There are clear signs that Putin is very paranoid of being replaced in the near future.
Several of the Russians I talk to think Igor Sechin is the one maneuvering for a palace coup. There's been a lot of "close Putin allies" who have died since the war started. Sechin runs Rosneft, so if anyone is positioned to "turn the gas back on" it might be him. If he was shopping around the idea "let's get rid of Putin, turn the gas on, and get back to printing money again"....Putin blowing up the pipeline as a necessary evil to kneecap Sechin......that sounds possible.
