Again I think this was just a mistake, but there are other groups that could want to add something like this other than the NSA where it would be more plausible for them to have such a need. It shows that Apple needs to reconsider its processes though, and I guess they are now, which should make the likelihood of something like gotofail for nefarious means working very small from now on.
I'm hoping that their security folks are now going through and writing extensive automated tests for all of this code, and anything similar, and turning on lots of automated static analysis to go along with it.
I fear that it may end up as, "we already found the bug, we don't need tests now". But that's probably pessimistic of me.
Of course, this presumes that the NSA needs to introduce bugs like this. I imagine they do just fine for now merely taking advantage of naturally occurring bugs.