Congress did a lot of shady things prior to the Supreme Court slapping them down in Powell v. McCormack in 1969. There are some in Congress who like to pretend they still have the power to do things without courts, including whoever authored your linked memo posted to congress.gov. It was only a couple years ago that Nancy Pelosi claimed she had the power to do such a thing when she said "If I wanted to be unfair, I wouldn’t have seated the Republican from Iowa because that was my right on the opening day. I would have just said, you’re not seated, and that would have been my right as Speaker to do so", but that isn't how the law works. Congress does not have that power. They are going to need a guilty verdict from the courts.
Powell vs. McCormack specifically excludes the 14th Amendment from its umbrella in footnote 41.
In addition to the three qualifications set forth in Art. I, § 2, Art. I, § 3, cl. 7, authorizes the disqualification of any person convicted in an impeachment proceeding from "any Office of honor, Trust or Profit under the United States"; Art. I, § 6, cl. 2, provides that "no Person holding any Office under the United States, shall be a Member of either House during his Continuance in Office", and § 3 of the 14th Amendment disqualifies any person
"who, having previously taken an oath . . . to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof."
It has been argued that each of these provisions, as well as the Guarantee Clause of Article IV and the oath requirement of Art. VI, cl. 3, is no less a "qualification" within the meaning of Art. I, § 5, than those set forth in Art. I, § 2. Dionisopoulos, A Commentary on the Constitutional Issues in the Powell and Related Cases, 17 J.Pub.L. 103, 111-115 (1968). We need not reach this question, however, since both sides agree that Powell was not ineligible under any of these provisions.
Any other sources?