TBH, that seems the more reasonable way of dealing with it. If they are truly worried about transmissions while in flight, then yeah do that. Once the luggage is on the ground and unloaded the AirTags will still work. Seems like a win win for everyone — if what they say about in flight transmissions is the real reason.
They are just tired of people with lost luggage making their staff go find it… there is absolutely zero risk, the amount of energy involved is minuscule.