Yes I would go along with the message of not overthinking it. In CS the idea of being "next" to someone is somewhat artificial since the sight lines are all about privacy. Even between E and F seats (so here I'm assuming 1A, 2A, 3A plus 2E) there isn't much proximity. If you needed to intervene with the child on E and F, depending on the aircraft, it may be almost impossible to attend to them if the meal service is on and you can't physically get to the other aisle. The "next to" requirement is a mix of statutory requirements - intepretation thereof - and a last manual check. So beyond the scope of robotics, but a process check to make sure kids are not exposed to unnecessary risk, e.g. in the event of a cabin fire. BA isn't systematically watching this until boarding is close to complete, and in CS the options are in any case limited.