I think my take on that, is it was just a poorly designed question. I believe the intent was that since the answer choices force you into making one of them a recommendation versus requirement, we get confused and interpret it as required in general. I think what they are doing is saying, hey… you have to have one of them, and since we know gross is recommended and not required, we pick net. Takeaway: In isolation either, if you have to pick one or the other that is required, net.
So I redid all of GIPS and of course couldn’t find a conclusive solution. Here is my interpretation though. EOC 26 lists a company that reports gross of fees and asks you show all of the omissions and errors they have. One of the omissions and errors is not that they reported gross of fees and not net of fees. Sample Company 2 in Actual GIPS Appendix reports gross returns only and is used as a template. Sample Company 8 uses net only. Answer is you can do either as we originally suspected. I firmly believe CFA Sample was not written by CFAi.