Yes, but you see, Paul wasn't one of the F&DS.
Nice try. You are correct! Paul wasn't, according to the new teaching. But he was on the 'governing body' back then, and said body is still nonetheless a precursor of the 'responsible ones at headquarters' today. So if Paul, who wrote Bible books and had visions and all that, didn't sit in council to make rules and "had no authority to do so", is there some reason why people who have none of those qualifications can do so today? If he couldn't, but the Governing Body today can, then the Governing Body is saying it has greater authority than the apostle Paul and indeed all of the apostles put together. Such authority cannot be merely stated; there has to be proof other than having a really good printing press and an advertising campaign.
Hey, if you're arguing the JW perspective and want to admit to that point, and you kinda have to, really, then there's really no point in continuing the debate.