I think it's a plothole, if you think that the Mangekyo was awakened for a moment,since we saw when he really awakened the Mangekyo...it maybe a healing technique, that he used to save just Obito's right eye,not his entire body,but I can't imagine his sharingan being the savior, because in that case Obito could have manage to slip through the rock with his entire right part of his body..