Judah wrote
Why would some wise-ass pilot try to pass off his own ambivalence as
some reg or policy?

Because he doesn't want his ATP Certificate suspended or revoked.

Section 121.542: Flight crewmember duties.
(a) No certificate holder shall require, nor may any flight crewmember
perform, any duties during a critical phase of flight except those
duties required for the safe operation of the aircraft. Duties such as
company required calls made for such nonsafety related purposes as
ordering galley supplies and confirming passenger connections,
announcements made to passengers promoting the air carrier or pointing
out sights of interest, and filling out company payroll and related
records are not required for the safe operation of the aircraft.

(b) No flight crewmember may engage in, nor may any pilot in command
permit, any activity during a critical phase of flight which could
distract any flight crewmember from the performance of his or her duties
or which could interfere in any way with the proper conduct of those
duties. Activities such as eating meals, engaging in nonessential
conversations within the cockpit and nonessential communications between
the cabin and cockpit crews, and reading publications not related to the
proper conduct of the flight are not required for the safe operation of
the aircraft.

(c) For the purposes of this section, critical phases of flight includes
all ground operations involving taxi, takeoff and landing, and all other
flight operations conducted below 10,000 feet, except cruise flight.

Bob Moore