>>>Russia appears to believe that cutting off gas to Europe will end European support for Ukraine, and therefore has an obvious incentive to cut it off. Russia has incentives to make this look like it isn’t Russia’s fault

Russia had already done the former by basically "turning off the tap", and already argued it wasn't their fault because they were willing to supply gas to Europe as long as Europe paid in Russian rubles. They were also using the gas supply for political leverage:

"release our frozen assets and we'll turn the gas back on" "pay in rubles and we'll turn the gas back on" "stop sending weapons to Ukraine and we'll turn the gas back on"

Now they physically CAN'T do any of those things, so this is a massive blow to what little bargaining power they hoped to retain through the winter. If there is any nation that is harmed by the physical destruction of these pipes, it's Russia.