Then explain why Russia had already cut off the supply of gas for clearly spurious reasons. And why Russia has used shutting off gas as an economic weapon before, including against Georgia and Ukraine in the past.
I’m not convinced Gazprom would’ve done this to get out of penalties, but your statement is incorrect. Contracts still matter because this isn’t an all out existential war where nothing else matters. Relations will have to normalise at some point, and Gazprom is still selling to other countries and can’t show itself to them as an unreliable partner that doesn’t care about delivery contracts.
Sending a message is not just about demonstrating the capability, as you’ve focused on, but showing the willingness to actually do it.