Whether or not that’s true at the moment (obviously, the status quo has changed because in 2020 UPlay changed to Ubisoft Connect, so the alleged incident happened years ago, and it’s alleged that Ubisoft were forced to stop selling something, so they wouldn’t still be selling it), the article specifically says:
Uplay featured a $15 USD Rainbow Six Siege Starter Pack, but this version was not available on Steam, making the cheapest option on Valve’s platform much more expensive.
The obvious way of parsing that is that it was the UPlay version of the game, but even if not, it’s generally not viable to sell Steam keys for things not available on Steam. The only time you can is when a game’s delisted but you’ve already generated keys for it, and then Valve can just wait for Ubisoft to run out rather than making the alleged threat.
Whether or not that’s true at the moment (obviously, the status quo has changed because in 2020 UPlay changed to Ubisoft Connect, so the alleged incident happened years ago, and it’s alleged that Ubisoft were forced to stop selling something, so they wouldn’t still be selling it), the article specifically says:
The obvious way of parsing that is that it was the UPlay version of the game, but even if not, it’s generally not viable to sell Steam keys for things not available on Steam. The only time you can is when a game’s delisted but you’ve already generated keys for it, and then Valve can just wait for Ubisoft to run out rather than making the alleged threat.