They – Colette, one of the most prestigious and influential boutiques in the world, who ordered $300,000 of SLP for next spring – stopped selling them after SLP asked, and SLP terminated the relationship anyway, claiming the shirts were "counterfeit" goods (come on).
There is no way to paint SLP's actions here in a good light.
I have a hard time believing the counterfeit sales damaged the brand, but can see where it could lead to if Collete continued to sell them [online]. Selling the rest of the stock in-store would make sense since 1.) the item won't be written off as a sunk cost on Collete's end even though it wouldn't be that much and 2.) have some form of damage control on SLP's end. SLP obviously wants to try to put an end to the "YSL ain't what it used to be and Slimane made it a jillion times worse when he changed it to SL" mentality the general public has/had. And plus, Kering prooobably doesn't want it to affect their stock price. Das what me thinks.
Ooh wee, I'll tell you what. It was a harsh way to end the business relationship, but damn, was it gnarly. I need to sleep.