If the story was true, only a few people in each company would have been aware of these vulnerabilities, and they might not have been allowed to talk to anyone about them by FBI. Then, even if others were informed, they would have to pretend, that they were not.
If it's a national security risk they might not have needed to be compelled to lie at all, but decided to do so themselves. This would be big enough to damage their entire supply chain if they did publicly verify it as truth.