Initially it was behind a consent form for research purposes. i.e. Just give some basic deets and you get access to the weights under a non-commercial license. FB shut that down after it got lots of attention.
That obvious got copy pasted onto a torrent & grew legs from there. And FB hassled some people DCMA takedowns too but seemed pretty half hearted & was too late at that stage.
[Sidequest: I believe the repo they used to distribute access also had a magnetic link in it too at one point which further confused the narrative but not 100% sure on the precise details on this]
Point is at no stage was this 100% behind closed doors and someone leaked it as you & I would understand the word in the "stolen" sense.
