STN and MAN are different though, Manchester isn’t London whereas Stansted is and there will be the cultural issue of pride and prestige to overcome in terms of the perception that LHR is the prize to be seen at. CEO X will not want their airline at a lesser airport to CEO Y regardless of its merits.
I’d also suggest the benefit of Cambridge in the context of a Chinese route is minimal, and STN’s best hope with the Chinese market is to poach LHR waiting room traffic from LGW. With a number of routes already at LHR, even that ship looks to have sailed.