First of all even if the reports were true they wouldn't be bad news at all. Zorc and Watzke would probably even be praised for making so much money off of Gündogan.
Secondly this was way more than your usual superficial denial. He seemed a bit pissed, called out the Paper and to a lesser extend Sky by name and pretty much labeled them unethical storytellers.
Dortmund's officials like to hold on to transfer/contract informations as much as possible, but usually they simply no-comment reports or give some cryptic answers/half truths.
Like for example when it seemed pretty obvious that Dortmund were gonna sign Tuchel Watzke went public and said that people shouldn't be so single minded about Tuchel in their speculation, that they would go with safety over tempo and that he didn't know who was going to replace Klopp in the summer.