To play devil's advocate, I don't see any evidence they're NOT training on user content either. Compared to how explicitly they indicate they're not using user content for targeted advertising, this seems like a huge oversight. Given how carefully they've put together these documents, I'm doubtful it was an oversight.

I think it's appropriate to be concerned and seek clarification. And I don't like people immediately seeking to vilify Microsoft as if they came over to their house and shot their dog in front of their kids.