I think leaking documents is very different than data misuse. Data misuse is harming to the individual, while leaking documents is harming to the company. As a matter of fact, leaking this document may even have positive effects in the long run on the behavior of the company.
The article specifically says that some portion of those terminated employees were caught sharing internal documents externally (leaking).
They both rely on the same mechanism though, just different impact and intent.