I knew this would come up.
PROJECT: Yasuo is different from a limited Edition Skin. Limited edition skins had the exclusivity the moment they were announced and released. PROJECT: Yasuo did not. That skin was never intended to be a collector's item like limited edition skin were. Changing some thing that was supposed to be special into something available to everyone made them go back and give something additional to the people that bought it during the initial deal, when it was supposed to be unavailable after purchase.
This is different from PROJECT: Yasuo. When it was released, Riot never made any claims that if it was bought during its first week or when it first came out it would have some kind of special border or would only be available during that time. Going back and making it special to previous buyers when it was never advertised as such doesn't make sense. It would have to have had this feature on release, and not having it could very well have been an influencing factor for potential buys to not drop RP on it.
PROJECT: Yasuo is not a limited edition skin and does not get the limited edition skin treatment. Sorry.
Similar, but key differences.