That's why I'm asking for the official answer. I don't want to spend time doing something that would let to disprove my work.
It is doubtful you will receive an official answer until you actually try it. If you were to ask about everything that isn't in the rules, you'll be waiting until Hell freezes over because the rules are deliberately not that strict.
Are you saying that the theme/mod may be dissaproved because someone 'feels' some sort of functionality is not necessary? Are you for real now?
No, I'm asking you if you feel the functionality is actually necessary. Most people don't update a theme much after it's been installed unless the theme is buggy, and even then they come back here to report the bug and see if there's been an update.
Plus there are a lot of issues related to updating themes so people don't bother - and thus having a 'has this been updated' check is often unnecessary.
The 'is it really necessary' stage is important because it's balancing a trade-off. If there is a problem with the theme, people come back here, and it reflects on SMF and its team, especially if they approve something that is potentially dangerous.
What happens if your site is compromised and people get their forums hacked? (This is not entirely a hypothetical question. It can and has happened before) Are you going to be the one who the users come after for help? No, they're going to come here and not really after you. On the basis of that, the team are the ones who have to make a judgement call whether this should be done.
There's no rule for it because it's not possible to write a rule book for every single thing that someone could or could not do. Thus a little intelligence is applied, and if there is code that generates a security risk, it's going to fail approval. And if that code is a lot of work for a feature that is impractical and no-one is going to use it, is it worth the effort?
Here's the thing: I've been on the approval team, seen some insanity in what people do and I'm trying to help you avoid burning a lot of time and effort on something that probably won't be appreciated in the real world out here, rather than your black and white hypothetical one.