Constitution>Laws so there is no MUST as the 5th wins. What do you mean by MUST though? Testify or be fired, reprimanded? Maybe that, but a lawfag would have to weigh in as to employee rights.
Anderson Cooper was confused if the twat was a double meaning or not. Cooper wasn't sure if Flynn Jr. was talking about him getting arrested or the orgy he setup for tonight. Hence why CNN thinks it was cryptic.