But that is not what you wrote.
The small mass that was coming from Earth and due to the transmission of the signal returns to Earth is the only thing relevant for the twin paradox (everything else either has not been on Earth or does not return to earth). This mass had a velocity directed...
Contradicting yourself here. From a general relativity point of view, sitting on a thrusting rocket puts you (and the rest of the universe) in a homogeneous gravitational field (just like you said) and, hence, is indistinguishable from standing on earth.
On an unrelated note: The scenario...