I am tempted to say I am wrong. The only thing keeping me from saying I am wrong is that the FAA doesn't require you to log PIC to stay current. The only purpose of PIC is for the aeronautical experience requriements of certificates and ratings. Once you have your ATP, the FAA doesn't see the need for you to log PIC.
That isn't all the FAA requires you to log
Sec. 61.51 - Pilot logbooks.
(a) Training time and aeronautical experience. Each person must document and record the following time in a manner acceptable to the Administrator:
(1) Training and aeronautical experience used to meet the requirements for a certificate, rating, or flight review of this part.
(2) The aeronautical experience required for meeting the recent flight experience requirements of this part.
61.51(a) tells you what you must to log. You need to log time to comply with various things such as 61.57(c). If I have an ATP rating and I go a fly approaches in a C-172 how would I log those approachs? I would refer to 61(b).
(b) Logbook entries. For the purposes of meeting the requirements of paragraph (a) of this section, each person must enter the following information for each flight or lesson logged:
(1) General --
(i) Date.
(ii) Total flight time or lesson time.
(iii) Location where the aircraft departed and arrived, or for lessons in a flight simulator or flight training device, the location where the lesson occurred.
(iv) Type and identification of aircraft, flight simulator, or flight training device, as appropriate.
(v) The name of a safety pilot, if required by §91.109(b) of this chapter.
(2) Type of pilot experience or training --
(i) Solo.
(ii) Pilot in command.
(iii) Second in command.
(iv) Flight and ground training received from an authorized instructor.
(v) Training received in a flight simulator or flight training device from an authorized instructor.
The only purpose of PIC after you get your ATP is to satisfy high min requirements or other regs that require you to have acted as a captain. Remember that PIC logged under the sole manipulator clause can't be used towards high mins.
That is going to be dependent upon the operator in question. Which is why many airlines define PIC time differently the FAA does. As I said in my original post being PIC under part 1 has little to do with logging PIC under part 61. Logging PIC under part 61 often has little do with a job application or an upgrade with a carrier. Regardless of how many hours you have though you are required to log time for the purposes of currency and you are required to log that in a method which complies with 61.51(b), if you aren't you are failing to comply with the regulations.