They could do that, but it'd be genocidal too, since without Russia the Chechens have no economy to speak about.
Fortunately (or, indeed, unfortunately) Chechens don't really want to cut all their ties with Russia. For instance, they're quite happy to continue their criminal business in the major Russian cities... all this 'national liberation' rhetoric is quite hypocritical.
How they manage to stew in their own juices would be nobody's business but their own. And if the place is walled off, it would be only natural to expect that the diasporic ones would be carted in, and dumped in there.