Not true!! In most parts of the world if you attempt to save a life in good faith then you are safe legally. In some parts called the 'Good Samaritan' clause.
This doesn't mean you throw common sense out but if the man is dying while everyone stands around trying to call medlink (not working) etc etc then you act. You act in the best interests of the guy that is dying and do so to the best of the abilities of yourself, those around you and within the scope of common sense and the 'rules' if possible.
There is not a court that would hold you responsible provided you did this. In fact in may parts of the world a doctor would be held accountable if he did NOT step forth and attempt to help. The same applies to anyone with any kind of training that might be able to help (or something as basic as a CPR course).
Now we can't comment on this situation because we were not there and I think that in most cases our FA's would handle it well.
But if THREE doctors have come forward and said something was amiss then I believe there may be more to it than meets the eye.