This would be like amputating both of your legs to avoid a military draft, it makes no sense. They're already fucked 10 times over, paying a fine is the least of their problem.

They're illegally invading a country and committing warcrimes, why would a fine be the red line, if they went ahead with the invasion I'm pretty sure they can say "no" to a western fine

Gazprom has much, much bigger problems than breaching that contract. I don't see how this helps them at all. If an EU court rules against them so what? No way to enforce the ruling.