I understand that, but it's just that Standing Order 111 states:
The committee, if it should call an appointee or nominee to appear pursuant to section (1) of this Standing Order, shall examine the qualifications and competence of the appointee or nominee to perform the duties of the post to which he or she has been appointed or nominated.
I would ask for your guidance here. Keep in mind as well that on I believe page 1068 in chapter 20 of O'Brien and Bosc, it is stated that when we do have public servants at committee, things such as policy or political decisions are not forced upon them. To give those answers might compromise their relationship with their minister.