Not trying to speak for Mike (I have taken Covert Carry twice and his Advanced Handgun as well) and not having anything in the same realm as his experience, my takeaway is the TI position is less than ideal even as a transitional position when moving, particularly in a FAMs or tubular assault position (where Mike says he was usually running the aisles to contact).
This is based on the fact the pistol blocks your vision and creates a very vulnerable blind spot. As it happens, in the most disadvantaged position to attempt to defend a weapon takeaway, much less one you can’t see coming. The alternative he presents is stronger, easier to defend, less obscuring, and still does not risk flagging unless you have someone eight feet tall hovering over you.
I also like his alternative to Sul, and have begun incorporating it into dry practice in the expectation of using it live in the future.