While one may choose to interpret the US FARs this way (God only knows why), the simple realities are:
1. In every interview with an American carrier (including the one I work for) I've been a part of, or heard about, the question is "How much turbine PIC time you got, bub?".
2. NOT A SINGLE SOUL in his right mind would advance to the interviewer the prospect of that PIC time having been logged while serving as second-in-command in a scheduled airline operation.
3. If one were to attempt this, he/she would be shown the door.
The only time this interpretation of the regs legitimately comes into play is in 2-pilot corporate or FAR 135 charter / cargo operations where a first officer may log PIC time if he manipulates the controls (assuming he is appropriately rated in the aircraft) during a ferry or reposition leg operated under Part 91 only. Some people try to "interpret" the rule a little more than that, but believe me any airline interviewer worth his salt will grill the hell out of them when he finds this in their logbook.
Therefore, the entire argument is irrelevant to FAR 121 / US scheduled airline operations. Don't log your 747 FO time as PIC. Trust me.