If you're trying to engineer loopholes out of citizenship laws, you're going to get yourself pulled aside.
The whole point of these arbitrary rules is entirely to make this sort of shenanigans impossible but to let in people who are using the system for the purpose it was designed.
That's why the rule about 'relevant to your travel' is vague. So that you can't weasel your way through it.
People who write this sort of app think border entry is two doors, allowed and denied. But there's also the guard who stabs people who ask awkward questions and their name is 'National Security'.
He's not trying to engineer loopholes. He's trying to comply precisely. You are right that there are some genuinely squishy things, but not all of them are. Tax residency is not a judgement call. Overstaying visas or visa waivers is not a judgement call. Residency requirements for immigration applications. etc
Unless you're rich, of course.
No, it sounds like the author is well aware of that, and is instead just trying to get a read on what the gov's various systems are saying about him, so he can stay well within buffers of that.
He explicitly says that none of his data on the app would convince an official.