Even if the Georgians in South Ossetia had boycotted both referenda, you'd still be looking at a more than 75% vote for independence. And I'm told that many ethnically Georgian Ossetians actually favour independence too - in the way that some English folk in Scotland support the SNP.
What would be the percentage of people in South Ossetia who would favour continued rule from Tbilisi? 10%? !5%?
The status quo simply can't be justified, however odious we might find the South Ossetian government and however much we might deplore the choice expressed by their people.
Would we have any right to prevent Ulster opting to become part of the Irish Republic if 75% in the North were Catholic Nationalists, and if, in a referendum, 98% voted for that - twice? We might regret it, (if you're like me you'd hate and deplore it), we might want to ensure that the interests of the minority were guaranteed, we might even want to offer them sanctuary. But could we ignore it and insist that Ulster remained part of the UK?