No, in the same way lawyers and the judge can decide ahead of time not to admit an unqualified expert witness, or to dismiss the jury for someone like Darrell B

No, in the same way lawyers and the judge can decide ahead of time not to admit an unqualified expert witness, or to dismiss the jury for someone like Darrell Brooks representing himself by bringing up irrelevant information and hearsay which is inadmissible in court. If someone says the wrong thing in front of the jury it is somewhat difficult to erase it from their brains or to convene a new jury.