That's kind of troubling, depending upon the details.
If I hire someone and he starts fishing around on the servers that he has access to, looking to put together a case, that could easily be a violation of trust. I could maybe even see if the SEC had contacted him and asked him for information as an informant in something ongoing. But Riordan initiated this - and it wasn't like the Uber example where Susan Fowler was exposing company culture information that was more public in the first place.
Granted, Rothenberg looks pretty dirty and I have personal experience with a CEO diverting company funds and priorities away from the supposed corporate mission. It's no fun and I have sympathy for stopping him.
If I hire someone to do some server work, I want him to do the job I'm paying for - not spend my money trying to build a case against me.