Not saying anyone should get sued; I just think placing an NDA on such a large group of software developers, preventing them from talking in public about software that they are developing, is completely stupid.
It's also interesting to note that this port couldn't have happened with the earlier NDA which didn't allow public release of source at all, since the port uses some GPL'd stuff. (Of course, Carmack could have re-written that stuff to avoid having to release the code, and he thought about doing that anyway for other reasons, as stated in his diary.)
I can't imagine what a PITA it would be to develop for a platform, especially a very new one, where you're prevented from speaking about things to such a degree. It's better than it was but you still can't post on a public programming forum and say "here's what I'm trying to do, can you help?" and equally people cannot say "here's a useful piece of code which could help you" until Apple have approved that code.
Apple still get final say on what does and doesn't ship, and they've had long enough to file patents for the thing. (Especially if you consider the millennia where there was no SDK for it at all.) It seems like control-freakery and nothing more.