Re: Heh
"Then again, if the employees were careful to hide any shady business in unrecorded chat messages, it only means that they'd have otherwise hidden their shady business in unrecorded meetings."
That's possible, but the other possibility is that they used chat because that's the typical system* and didn't take any action either to preserve or to hide their messages, allowing Google to decide what to do with them. Had Google had a retention policy that kept them, the messages could still have been there. This is more likely to be the case when the employees are implementing something the company knows is illegal but the employees don't know, whereas employees doing something they know could land them with a criminal charge would likely be more careful with their comms.
* In one company at which I worked as a student, so many systems were set to send emails to everybody, including many people who not only didn't care about what they said, but also wouldn't even have understood what they said, that email was no longer a reliable way to communicate with anyone. You could send an email and the people who set up filters to eliminate enough of the junk would eventually see it, but even for them there was enough junk left over after filtration that they would only look at email infrequently. The internal chat system became the only way people tended to communicate with one another.