You are kidding right. An anonymous posting on some Internet site is evidence of what to you? You have to be a little more critical that that. It is evidence that someone made a posting, but not evidence that anything actually happened. I am sure they will look for that evidence.
What would you have them do, based on an Internet posting? Start questioning 32,000 employees? C'mon
It is "evidence". I didn't say it was "proof". The two are not the same concepts.
They should follow up the evidence they have however they can, but they are wrong to say there isn't any "evidence".