I understand the intent of the removal of subclause 17(6) is to prevent the commissioner or the president of CBSA from refusing to provide certain information. In fact, that provision doesn't allow the commissioner or the president to refuse, it merely says if they do refuse, this is what they need to do in refusing it. They need to provide the commission with the reasons they have determined that the information is not both relevant and necessary, and give an indication of the nature and the date of the information.
This would then enable the PCRC to determine whether or not the commission actually needs the information and whether to pursue other options, such as perhaps a judicial review application to the Federal Court, to try to obtain the information.