The larger part of the infringement is probably its use commercially. I doubt that there would have been such a fuss if it was a fully-open, low-profit operation.

But as-is, the commercial products are being used to make money for the AI company in an unauthorised way.

Similar to how it's generally frowned upon for fan media to make money, because it starts being infringement. You can have a "support the fan media maker" button, but you generally can't do things like put your fan media behind a pay wall. The IP owners will come down hard on you for that.