Correct . The difference is between the the verbs Can and May. However the Courts have taken the view that it WAS illegal ,and MAY be appealed .They also effectively rescinded the Stateless state, by giving her permission to present her appeal.It can and the proof is in that it’s been done. She is no more a U.K. citizen than she is an Irish citizen.
Taking pride in a Government doing illegal activities, in the cases where you approve of their stance is extremely foolish and short sighted. A Government is responsible to the people for the maintenance of LAW and order