I can't find data to support my speculation but I'll share it anyway:

1. The things the west has banned importation from Russia, and the things that Russia is banning exportation of, may not be the same. Therefore, Russia may cause pain by blocking the export of some things that were previously available.

2. The West previously controlled when the end of this trade blockage happens. Now Russia also controls this and the timing - what was previously a boolean is now an AND.