Barr volunteered to sit before these dummies. That was before Nadler denied minority rights in the House to push through a vote for secondary counsel to question him. These were not the conditoons agreed to, so he said no.
CO-EQUAL branches of government. The Executive is not submissive to Congress, and the unredacted report was offered to members of Congress, but because this is all a charade only Republicans read it.
The report has been released. Barr's summary of Mueller's conclusions, which Mueller agrees with, is irrelevant.