He gets to force the EU to walk back on the restrictions imposed on Belarus. Russia’s interest is to stop the EU from advancing (in any form) over Eastern Europe.
If Russia's goal is to stop Eastern Europe to become unfriendly, then they already fail, since most of countries that Russia themselves consider "unfriendly" are already in that region -- Lithuania, Latvia, Estonia, Georgia, Ukraine, Poland, Czech (in addition to the US and UK)
He wants Easter Europe subservient and afraid, not "friendly".
Good point about resisting EU control of Eastern Europe, although this doesn't seem like the optimal way to do that. Maybe this is step one, then step two is to cut a deal that imposes some limits on Belarus' actions but puts Russia in the control seat of negotiations etc.