As am I. The paper dedicates one sentence to that question: "... another aspect that needs to be studied is whether its extremely low density could be maintain

As am I. The paper dedicates one sentence to that question: "... another aspect that needs to be studied is whether its extremely low density could be maintained while in the parent system, during its long interstellar journey, and when entering the solar system." Without analyzing the structural integrity of such a fluff ball it's tough to give any more or less merit to this concept than the others.