Who cares if they haven't read it. That's not important.
What's important is: they've had the ability to read the report, in full, outside of grand jury information, and they're throwing a hissy fit over Barr misrepresenting the report and withholding it from them. They held Barr in contempt for one of two things: withholding something he's not withholding, or withholding details that he's required by law to withhold.