I would agree with this, but it is unfair to everyone who bought PROJECT: Yasuo when he first came out. He is the first project skin and the people who bought him when he first came out, would get nothing.
If it was possible, I would suggest giving a special boarder for those who bought PROJECT: Yasuo within the first week of his release. Not for those who are just now buying the skin. It's a limited edition deal for a reason .
They did this because there is a ton of them and they are all really expensive, so they have created an incentive for people to want to buy them full price instead of wait for them to be on sale or not buy them at all.
Hence why Project minions are something you can get, and the special loading in animation.
Most people aren't going to be interested in buying them unless they come in a bundle that's just a bit cheaper then full price. As the comments below wrote in the link you posted.
People willing or able to buy them full price, right at release, deserve something extra and limited. This wasn't an option for people who bought PROJECT: Yasuo to start and I don't feel like they should just make an exception for new players buying an older skin.
EDIT: I just made a comment, including the point that Yasuo's skin was released at the discount price. So it really isn't fair to just give those who got the skin for cheaper, a boarder that is meant to be a prize for buying the skins at full price.