The Tsar was political deadweight by the time the execution actually happened, I agree with tank in that a murdered royal family down to the last child is a far better rallying point for the Whites than anything else. Sure, some of the Whites did actually want the restoration of the Tsar, but the writing on the wall was already against that: the Tsar hadn't been deposed at the end of a bayonet point, he signed his own abdication document from a train car. It really dampens the claim that he was taken from power against his will.