I can understand the reasoning, even if the models don't pay taxes since their job is Illegal in Russia the money will still end up in the economy. It's the same reason we do all the other sanctions.
I does seem slightly pointless though since neither SC or DC do the same. Most users will just move there to view the same models in VR. I think most of us only use SLR because the app is simply better, but doubt many of us would stop going to our favorite models just because we'd have to use a worse app.
Let's just hope this whole mess will be over soon and someone removes Putin and his buddies from power.