Cutting Russia from SWIFT is not like cutting Iran off. Russia is way richer with far more reach and cutting more and more countries off of the network will give more and chance for one of the alternatives to grow.
Cutting Iran from SWIFT has also just created pressure on Iran to not rely on foreign economies too much. And you can see this by how they've essentially become immune to more sanctions, or global economic termoil. Honestly cutting Russia off of SWIFT is going to create a much more dangerous Russia in the next few decades.
Yes, it's an age-old dilemma, to try to soften the aggressor or to stand up to him. Delaying the confrontation hoping something will change for the best vs standing the ground and fighting back.
Some lessons from the not that recent history might suggest that choosing the former might lead to quite a disaster.