That’s a great question, and it’s (relatively) feasible to answer. The object is coming in towards the center the solar system, so its past trajectory lies outwards. If it has been disturbed into this path from a hypothetical sun-centered orbit, it would have to have happened very recently: otherwise it would be long gone, never to return. So it would be necessary for the back-projected trajectory to pass very close to a compact, massive object. Dare I say that the vast majority of all such massive objects in the solar system are well known; so if the trajectory doesn’t indicate a close encounter with a planet within the past decade or so, then this possibility is essentially eliminated.