My understanding is that the authors of the paper were speculating that this object might be debris from an encounter with another star that later flew by our s

My understanding is that the authors of the paper were speculating that this object might be debris from an encounter with another star that later flew by our sun by mere coincidence. As far as I can see, the observed hyperbolic trajectory doesn't seem consistent with a scenario where the target of the sail's payload would be our solar system.