Well the only reason you are perplexed is because you don’t grasp basic economic reality that suddenly shutting off the gas would destroy the economies of Europe.
Europeans themselves have said so.
If they have some years they can adapt and substitute in an imperfect fashion, but you do it at once and it’s catastrophic. Also coal does not really substitute everything gas is used for, there are a lot of industrial uses you can’t just readily replace gas with.
Also Europe isn’t all on the same page on sanctions as much as you might guess, despite them wanting to keep up appearances.
Then said Europeans should shut their mouths about engaging in proxy wars with Russia if they have no interest in actually decoupling from Russian gas that is funding the same invasion they like to virtue signal about opposing.
The Germans have said it will take years to construct the infrastructure to handle LNG from other sources. It starts with the ports and then the new pipelines to connect to the existing system.
And who will supply the LNG? The US can eventually, but the Biden Administration is blocking the expansion of supply and infrastructure.