If you had read the news - proper news media that is, you would have seen that the agencies DID NOT postpone their meeting with trump.  They were always scheduled to meet with him on Friday, AFTER they had submitted their report to the current President.  The hearings are an attempt to make trump realize that he is in the absolute minority in denying Russia's hacking. He's most concerned that it casts doubt on the legitimacy of his election - and so he should be.