I can see two likely scenarios why this got passed:

1. The reviewer has never used vim. As someone unfamiliar with vim, it never occurred to them to type :q, and thus they never saw that behavior.

2. The reviewer has used vim before, and knows how it works. With that familiarity, the reviewer understood that :q quitting the app was the behavior that users would expect.

This may be the one-in-a-million chance to disregard that guideline. A big rule in interface design is to do what users expect. In Vi/Vim, this means quitting on :q. Assuming that this is non-standard enough that Apple would go find somebody who knows Vim to handle the review, that person would (and obviously did) know this.

How many apps need an exit button? Just because you look around the App Store and don't see a bunch of apps with exit buttons doesn't mean it's because they aren't allowed. It never even crossed my mind to put an exit button in my apps because it's not a use case for my apps. I'm sure it's the same with a majority of the other apps.

Waze has a "Switch Off" command, although that seems to make sense since it's a way to stop running GPS.

Maybe they got a pass since ":q" is a basic Vim command. People are going to type it - what should they do instead? Nothing?