Agree. The question comes up why a 'method' is needed at all, especially all these complicated contrivances that seem to serve zero purpose. There seem to be two camps of physicists: Those that support a preferred foliation of spacetime (absolutists) and those that do not (supporting relativity of metaphysical simultaneity). In the former camp, what Bob does has zero bearing on what Alice's age is at a given moment in his travels. Hence they would never support any of said methods, none of which are objective. In the latter camp, the wording you use suggests that Alice has an actual age simultaneous with Bob's turnaround event, which any relativist would say is a frame dependent relation, and Bob has not explicitly specified any frame. The frame used by CMIF seems an unintuitive choice for a person undergoing acceleration. Neither group of physicists would say that Alice actually ages backwards because of what Bob is doing, so none of them should find anything repugnant. Yes, in any accelerating reference frame, sufficiently distant events from the accelerating worldline are beyond its event horizon and thus don't have meaningful current times. This is not repugnant, it just demonstrates that accelerating frames do not foliate all of spacetime. Stars 20 BLY away have a negative age in Earth's inertial frame, so they don't really exist in that frame despite the fact that we can see them. Hence the cosmologists needed a better coordinate system than the one SR gives them, but in doing so, light no longer has constant speed. It is only c locally, and SR becomes a local theory. So CMIF is a local method in a way, and if Alice is aging backwards, it's because she's not in the local region where the method doesn't do stuff like that. Minguzzi similarly uses a method that is frame independent, but does not foliate events that have space-like separation from the reference event, and hence cannot state the current state of any worldline outside that region simultaneous with an event inside the region. SR posits that light speed will be locally measured to be a constant, which is not quite the same as your statement here. Einstein is very careful to point out that it is an assumed convention that light speed relative to an inertial frame is constant. That convention is not part of the premise of the theory. It essentially assumes for convention purposes, that, relative to some frame, light travels the same speed one way as it does the opposite way. This of course cannot be empirically demonstrated, despite the fact that the earliest measurement of light speed used one-way methods, not any sort of round-trip signal scenario.