If Mr Bista is an American citizen,I think he can file a lawsuit against ambassador for committing act of threat. Mr ambassador may have an immunity, but king will be in the grave trouble. Even if Mr Bista is not an american citizen, if he has such an email, he can still go to the court and FBI and lodge a protest. There are legal avenues. Ambassador Shrestha has clearly crossed the boundary and he should be aware of it. But may be he did so to please his master back home, and this news probably did more benefit to him than less. Who next? Nepe?