No this should not happen.
No there will not be a blacklist.
Doing something about the situation is difficult due to lack of witness to back-up complaint. Was the abuse simply a venting of frustration or an attack which in a different environment could have resulted in the matter being reported to the Police.
Problem is that legally, no crime has been reported and there is no witness to the situation. Therefore as it stands, the CAA will find it hard to act on that basis alone.
However, the RTF / FTO are within their rights to refuse further service and the Examiner is within their rights to refuse to fly with the individual.
A report should be made and the CAA could interview the pilot to get their side of the story but unless a crime has been comitted it is very hard to find a legal basis for action.
Unfortunately the fact that your friend has cosen to discuss the details of the cvonduct of the test outside the circle of Candidate, Examiner and CAA puts the CAA in an awkward position regarding confidentiality.
Lesson to be learned - if this happens, terminate the situation politley and report the matter while maintaining confidentiality. If the level of abuse dictates do not be afraid to call the Police.