It is true that the Constitution assigns the president the sole power to nominate and appoint officers of the United States. It is also true that the Senate’s power of advice-and-consent is the principal constitutional check on the president’s appointment power. (U.S. Const., art. II, sec. 2, cl. 2.) It does not necessarily follow, however, that Congress may not impose qualifications that any nominee must meet when the office in question has been created by Congress.That doesn't sound like he's looking for a totalitarian leader to make him safe by imposing a fascist worldview and brooking no opposition. It sounds like he's thinking seriously about the constitutional separation of powers, and a due and proper role for Congress as well as the Executive.
What are now the Department of Defense and the position of Secretary of Defense are creatures of statute. The 1940s-era statute to which Shannen refers as the source of the limitation on the president’s appointment power is the National Security Act of 1947. It is section 202 of that act that establishes the Secretary of Defense – the office, the qualifications to serve in it, and the attendant duties.
Such are the terrifying creatures with which the Left now has to reckon.