This is the key in the article against a referendum:
There is a positive aspect to the idea: Putin seems to have demonstrated an awareness of the need to seek an exit from the Donbas morass his imperial “Novorossiya” fantasy created. After having been forced to intervene with regular Russian forces to prevent the collapse of his destabilisation scheme in eastern Ukraine, he is now stuck with the Donetsk and Luhansk pseudo-statelets there, which depend on Kremlin support in virtually every respect. The venture has become a political embarrassment, an economic burden, and a huge obstacle to Russia’s foreign policy ambitions.
If it is true that Russia made the offer out of weakness, the clear thing to do is absolutely reject it.
Ukraine and America have no reason to help Russia heal that kind of gaping self-inflicted wound. Short of absolute Ukrainian victory in the Donbas with a Russian withdrawal and payments for the destruction they caused; and a Russian commitment to returning Crimea to Ukraine, why would we have any interest at all in helping Russia reduce the pain they are experiencing in the current stalemate?