Why all the negativity about the possible Hainan Airlines MAN/STN deal?
I don't think it's going to endanger MAN in any way. They could just as easily axe MAN if it didn't work for them. If there's a financial deal or package for Hainan to use both MAN and STN then that will help secure them at both airports for a longer term future. That is only going to be beneficial to the MAG group and indeed for Hainan Airlines.
Please also remember that STN has and still is seeing quite a few changes since it was released from "the dead hands of the BAA monopoly" as MOL quite nicely puts it (who's airline just as an extra point is now also the largest at MAN). Also, in fairness to STN, much of it's long-haul operations were operated by carriers who went bust at the start of the economic crisis.
It's not that there's not enough demand for long-haul from STN believe me! No airline under BAA's monopoly whereby competition was restricted with LHR could make STN profitable. Maybe the new ownership might just solve that issue.
Of course nothing is confirmed yet, but if they do announce MAN and STN flights, that is in no way a threat or of any disappointment to MAN.