I'd think it would have been pretty awkward. The island, is not especially wide with staircases taking up most of the width on some sections and narrows towards the ends. Also being a platform island on a viaduct, acess seems pretty limited.Could they not have done half at a time rather than closing it? It would have required special crowd control measures (i.e. physically preventing people going down until their train was next) but with reduced numbers of passengers over the "interval" period it would surely have been workable.