You're a friendly fellow aren't you?

First of all, we have two different interpretations from the FAA. One that says you can log and act as PIC with the flying pilot, and one that says you can log and act as SIC only. The interpretation you referenced is much older than the PIC interpretation.

As far as the written regulations are concerned, not the interpretations from counsel, it would be in violation to log or act as SIC in an aircraft that does not require an SIC pilot. 61.51(f)(2) only gets you out of the currency and training requirements to fly as safety pilot in a 2-pilot aircraft.

BTW, there is no "precedence" in the world of regulation. Interpretation is subject to change at any time the administrator feels it should change.