It has become a mootpoint, but from now on they can always explain the good result by the fact everyone who wanted to vote no, didnt vote, and they wouldnt be far from the reality, increasing the legitimacy of the referendum result and accusing the poor democratic response of the anti-russian Crimean people...
If everyone would have voted and the results would have been the same, at least they would have felt the hypothetical electoral hold-up.
The complacency which comes with boycotting only works with commercial products, not with elections.