Blimey, there are some delusional people here about the power of Stansted.
It absolutely hasn’t proven itself. Both Maxjet and Eos went bust. So did Silverjet at Luton even without any help from AA. And then so did Primera. No-one has gone near either market with a premium product for the better part of a decade.
If jetBlue can get access to LHR as they seem to have, it’s absolutely the right place for them to be.