No, I don't think it would. First of all, I have a great deal of admiration for the legal minds at the commission. If it really wants to do something, it will find a way. The second point is that the commission has already, essentially, regulated users of the broadcasting system through the 1988 online programming guidelines. The commission did not regulate individuals calling into phone-in shows, it simply regulated the broadcaster's decision to carry specific individuals calling in. It did indirectly what it chose not to do directly. That's the point.
All you have to do is get the platforms in a room, ask them to develop a code of conduct, and then have somebody enforce a code of conduct whose effect is to regulate users.