Astonishing claims re STN/TCX from Flightrider which have to be regarded as just personal assumptions at best.
More reasoned posts above in answer have almost certainly highlighted the salient points regarding the TCX long haul withdrawal for 2019.
It might be thought too that with the TOM long haul withdrawal earlier TCX saw no marketing/operating/competitive reasons to maintain an outlier base but to require potential customers instead with no other choice than to decamp to their base at LGW.