nor shall be compelled in any criminal case to be a witness against himself
you can split hairs pretty good nigel. i'll give you that. but a case is not always conducted in a courtroom. it starts on the streets, questions, arrest, custodial arrest...and so forth. you can be a witness against yourself in an interrogation room. however, we know that is not the case because we look beyond the specific language.
i win, i split the hair finer you...i'm to a fire in five
Alright, let's look at the term "compelled." Can police compel anyone to participate in a criminal investigation aside from testifying at trial? Can the police compel you to be a witness against yourself in an interrogations? Of course not. Can you be compelled to testify in court even if you don't want to on matters that are not self-incriminating? Of course. They can throw your ass in jail until you decide to cooperate.
Taking the language as a whole, it is clear it applies only in a courtroom.