This happened to me recently, with Facebook. However, Facebook didn't reactivate my account, I was the one who mistakenly clicked on a link on Spotify when I reactivated my account which somehow triggered the reactivation.
I'm going to guess that OP of article had a similar situation; Using another service, an errant click was made that triggered an event on Facebook.
Facebook will do whatever they can to keep your account active. The shutdown process is a pure embodiment of dark patterns, and a single click reactivates the account.
I remember shutting down my account and then recieving some emails a week later, clicked the link wondering why FB was still emailing me, boom account reactivated. Shut it down again, then a couple weeks later I clicked the wrong share link and once again my account was reactivated.
If I was an investor or advertiser, I would be deeply suspicious of Facebook's metrics...
I'm going to guess that OP of article had a similar situation; Using another service, an errant click was made that triggered an event on Facebook.