Inconsistent line

"Facebook's spinners had taken the slightly inconsistent line that the code was useless and no security threat, but that posting it was super-illegal."

It's not really that inconsistent. They've just chosen to assert the rights afforded them by the DMCA, as the material is copyrighted and is not released under an Open-Source license.

The code itself is pretty innocuous. The developers have quite sensibly decided to abstract all their interesting stuff into lower-level functions, and the leaked code is just a bunch of API calls. Their "cease and desist" notices are probably prompted by the developers' equivalent of wondering whether they've left the iron on. Or maybe they're embarrassed by the comments:

"Holy shit, is this the cleanest fucking frontend file you've ever seen?!"

Yes, Mark. Yes it is.