Comment by jeroenhd

My guess, assuming the company is innocent and that this wasn't just a thinly veiled attempt by Google to purge the developers' gambling apps:

Google bans accounts by association. One of their accounts was logged into during a hack. They blocked the device, but the notification usually comes only after the login has already succeeded.

Assuming this wasn't the criminal's first hack, their device probably got flagged before by Google. If Google applied their logic to that device, they flagged this company's account (and probably all of these people's own Google accounts by association).

Google won't comment on this so I suppose we'll never know for sure. However, when the next company that the people behind this startup joins also gets banned, I'd consider the viral properties of Google bans proven and these developers could be considered "tainted" by our tech overlords.