I think this is going one of two ways: Either the official client is a quick bid to incentive Microsoft to remove 6tag the same way Microsoft replaced their YouTube app with a gutted one, or Instagram think their official client is going to rapidly eclipse the "knockoffs" and they won't have to worry about it.
Keep in mind that while Microsoft did cave on their own YouTube app, it wasn't in exchange for nothing at all. They still got to keep a gutted "official" YouTube client in order to fill checkboxes in pundit comparison reviews.