Author of the article here. Since I first published this blog post I was getting messages from people asking how it ended. Sadly it's pretty anticlimactic as the owner of the place had a meeting with the guy who put the Pi there (without me as he didn't want the Pi-dropper to feel ambushed) and in the end decided not to escalate it to legal and just basically told him to pack his things and get out. So no legal after…
Seem pertinent to atleast get an affidavit from the ex-employee detailing what he as done, agree to hold on to the hardware as evidence, put liability on the employee for any time-bombs that might have been stored, ask him explicitly to give in writing all the activities he performed, etc. Just to have a thread to pull on, in the future, when something might go wrong.
In his statement he wrote that the pi logged to the SD card but there was no data on the SD card (well not on the data partition) and I'm pretty sure that was a lie and it just logged to Balena.
But even though we could never decipher what the nodejs program actually did (because it was so heavily obfuscated) our internal working theory is that he was tracking the movement data of the boss to avoid him whenever possible.