The spokesperson had no choice. Speaking publicly in ways that harm the company's brand is against policy, a fireable offense.

Maybe an intrepid journalist could find out...

Perhaps, in doing so, that journalist would discover that Amazon had no real argument for any internal policy being violated at all. Or perhaps they would discover that these employees did, in fact, violate some internal policy, whether or not their firing violated their rights.

Which is why these things shouldn’t be decided in a court of public opinion. If you’ve ever been involved in the employment dispute world, you know there is a lot of liability for employers talking about internal investigation matters publicly. It’s not realistic to expect Amazon or any employer to talk openly with the press about an ongoing dispute with an employee in detail. Meanwhile, an individual fighting the company has every incentive to air everything (as they understand it) and little liability for doing so. Consequently, news stories are seldom going to give you a full accounting of facts.