In the context involved, the postulate is based on the "frame dependent measurements" involving the relative "t" for each frame the measurement is made in to give rise to the "postulated" invariance". Get it? The rest of your disconnected fixation on isolated remarks is also of equal worth. Hence eminently ignorable as mere opinion lacking in contextual understanding of the points as made in context. If you could ever rid yourself of the intellectually limiting habit of taking things out of context and ignoring the overall thrust of the aguments made, you would help your own understandings and not be found so wanting as an 'expert' time and time again. Thanks anyway for your interest if not your bad intellectual habits.