It would actually be a really interesting study, if they would ever be willing to be transparent about this, how the result differs with and without his conversations in the training set. How quickly it arrives at the result, whether it takes the same approach, etc.
Personally, I would expect them to have a little class, to KYC, and to manually turn off training for known competitors using their service so as to avoid any unforced goofs like this.
Yes. They should determine if training data included this teams data. Consider the money they spent, the press release and the purpose of their publication.
Since they failed to answer this question they shouldn't have published.