I can't speak for the B787 but while it is true to say that the CCM requirement is 1 per 50 and part thereof (e.g. 2 for 51 pax, 3 for 101 pax etc.) there is also usually an absolute minimum crew compliment for dispatch regardless of pax numbers (assuming it isn't empty).
As for the refuseniks, if they genuinely felt in danger then they were correct to leave the aircraft. However, assuming the absence of a specific violation to point to (e.g snow on the wings, out of hours etc), they immediately should seek a different career.
Calling the boss, and he most certainly is the boss, incompetent, unprofessional or reckless, requires a very good defence in any line of work. Accusing him/her of talking down to you, after you question his professional integrity, doesn't quite do it.