Mr. Bezan, you're quite right. When a witness appears before a committee, refusal to answer is not applicable. However, if a witness cannot answer because the question is beyond their responsibilities or scope, and there's a good reason, the witness would then raise that with the chair and the chair will determine whether or not the witness will be permitted not to hazard....
It's not for us to make that decision for the witness; that is the essence of the rules. But it is ultimately up to the witness to determine whether or not they're going to stray beyond their knowledge or expertise.