Has the republican Government given citizenship to the Swiss-born UK-citizen? There was never any communication around it.
King Michael of course was a Romanian national when he went into exile. That is different from Nicholas.
I am quite sure I have seen somewhere that he became a Romanian citizen in 2012, but it seems difficult to find a proper source for it.
On a slightly separate note, it seems from certain sources as if the decision of the King to remove Nicholas from the line of succession and withdraw his title, was indeed his own call, based on what he saw as a failure to understand and accept certain regal principles, such as dignity in public (the King allegedly disliked Nicholas being photographed and participating in sporting activities, such as cycling, ungroomed and folksy) and his wish to move out of Elisabeta Palace, and into an apartment, to be able to lead a more practical existence.
It would in many ways explain the statement made by the Royal House, about certain principles etc., and that there was no point looking for another reason, as there was none. It would also add to my view, that the King made an arbitrary decision based on outdated values, but that there most likely was a disconnect between grandfather and grandson about how royalty should present themselves and live.
If, and that's a big if, this is indeed the reasoning behind the removal of Nicholas from the Royal House, I am quite sure that it will be reversed after the passing of the King, and that the role of Nicholas in Romanian society is not over. Time is on his side on these matters, and it seems to me that the decision of the King will be understood one way, and the reversal of it accepted, as Nicholas frankly managed to get more respect and acceptance from many Romanians in his few years of service than most other members have in decades.