Probably for the  same reason he could not arrest Hillary on day 1. He has to demonstrate to the people what they are, he does no have the media so he must carry the people. It is interesting to watch, I am trying to understand the dynamics. Sometimes it seems that Pres. Trump  has the upper hand, just now they seem to be dominating the timetable. However, Trump will have a plan and at the right time the table will be flipped.