They're saying that the investigative team brought in to determine if there was anything they could be sued over found no evidence/email trail for the specific things that they could get sued over.
"We didn't find an email trail that could lead to a lawsuit, and the co-founder in question immediately resigned" is a very far cry from "Everything she said was a lie."
"We didn't find an email trail that could lead to a lawsuit, and the co-founder in question immediately resigned" is a very far cry from "Everything she said was a lie."