That's a broad definition of "Operational Reasons" (but as you say none of it is explicitly defined). Perhaps jb747 may wish to comment on his view of what that means in practice (yes, you may have to give some of those seats you own
).
I mean where a kid sits is, in general, not going to impact on aircraft safety or performance (unless it's a Brasilia or something tiny). It IS a safety issue for the passengers but not for the aircraft... same with someone with special needs, wheelchair etc (execption exit rows, but we all know those have special conditions attached anyway which crews check every flight).
So do we consider pax issues like this as commercial or operational?
Again I do recognise QF (or any carrier) can do what they like. I agree seats assignments are not guaranteed etc.. I totally understand all of that. I'm more about the principle. If I'm swapped to another seat so that someone else can occupy that same seat in the same cabin then that has zero implications on aircraft operations and safety(unless AM). That's my point. I do not consider someone wanting to sit with someone else to be an operational requirement, but a request. Simples