But legally, I think this code was stolen. Facebook owns the copyright to the source code, so copying and distributing is theft in the same way that copying and distributing database contents is theft.
But again:
https://legalbeagle.com/8608294-difference-between-larceny-t...
> In many states, "theft" is an umbrella term that includes all different kinds of criminal taking. This is the case in New York. Under the New York Codes, theft can be any type of taking, like identity theft, theft of intellectual property, theft of services and theft of personal property
To a lawyer, bits have color: https://ansuz.sooke.bc.ca/entry/23.
I know specially the film and music industry put a lot of effort to equalise those terms in the media, yet they remain two separate things.