Huh? You got a chief counsel letter to back your opinion up? The usual suspects, Nichols etc, are mute about this. They only refer to SIC ops in single pilot planes (Cessna 525-series in the Nichols interpretation, for example)

I can't find anything regarding logging PIC as sole manipulator of controls in an airplane requiring two crewmembers? But since you know so much more about this than I do, please enlighten me.

I would say a reasonable interpretation of the regs is, that if you are the sole manipulator of controls in an airplane requiring two pilots, you are in an emergency. Then I'd agree you can log PIC under 61.51(e)(1)(i).

61.51(e)(1)(iii) directly contradicts you anyway.

(iii) When the pilot, except for a holder of a sport or recreational pilot certificate, acts as pilot in command of an aircraft for which more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is conducted

ACTS as a pilot in command.

Sorry, but you are 100% wrong if you think you can log PIC by being sole manipulator of controls, in a plane requiring two pilots.
Unless you can find a chief counsel letter that contradicts this.