Apple has a point
Yeah, that'll get me downvotes... (no, I don't like Apple either, or the DMCA, or its use)
1) They have a point. The code was leaked unlawfully, in contrast to some other company who uploaded code & encryption keys themselves and made them public - oops!
2) The bird has flown. Like a bird, a word you say cannot be caught again once you let it fly. Same applies to stuff on the internet. Even if Github complies...
3) Yes, it's against the letter of the law - but this time not against the intent. Usually it's the other way round ;)
4) If I was an Apple lawyer, I'd write me a script to follow the branches on Github, send out an individual letter for each, with individual bills.
Biting the hand that feeds IT
