“Far from ‘fishing,’ or looking to the former President and his advisors as a ‘case study,’ the Committee is investigating events involving [Trump] and other White House officials that have an identifiable factual foundation and relate to a specific, unprecedented attack on the Capitol. That investigation unquestionably serves legitimate legislative purposes. And contrary to [Trump]’s contentions, those legislative purposes are sufficient to support the Committee’s request even if some Members [of Congress] also believe that the investigation may ‘disclose crime or wrongdoing” write the Justice Department lawyers in Trump v Thompson et al.