Sometimes there's only one good example of an uncommon interaction, so it's hard to extrapolate how that sort of interaction ought to work in general. What seems right in the moment for that particular case might turn out to be a poor fit when the design space is explored further. (For a simple example of this, consider the game Stage caused by the early-placed Stage III card against The Kingdom of Brandenburg-Prussia Level 2+.) Changing the ruling later comes with the cost of players having to re-learn the interaction when the ruling changes, with many not even realizing that it ever changed.
Nevertheless, not having a ruling leaves the question unanswered for years while waiting for more examples to arise. A ruling tagged "Rulings Under Examination" gives players a workable answer in the short term, but signals to players that they should be prepared for the possibility they'll eventually get a different answer.