President Trump has been insisting that the Mueller report amounts to TOTAL EXONERATION, having proved NO COLLUSION and NO OBSTRUCTION. As of Friday, he registered no objection to the author of that exonerating report, Robert Mueller, testifying to Congress.
Now Trump is demanding that Mueller not testify.
One answer to his question of why Congress would want Mueller to testify despite his “strong NO COLLUSION conclusion” is that he did not actually reach such a conclusion.
It is comically obvious that Trump relied on William Barr’s summary to shape a media narrative about the Mueller report that is not reflected in its actual substance. Trump fears a “redo,” i.e., Mueller having the chance to summarize his own work, rather than having his loyal attorney general do it for him.