[deliberately ignored two preceding lines]
   |         - the clock of S shows an elapsed time t = 2T
   |         - the clock of S" shows an elapsed time t" = 2T/g

BTW, since you are so blind to a contradiction, here's one for you:
"if T = 5 years and v = 0.8c, then the stay at home twin will
have aged 10 years"
   https://home.deds.nl/~dvdm/dirk/Physics/TwinsEvents.html