I have read over the paper. Interesting points are made.
I believe we will know for sure one way or the other after it goes around the sun. If it slingshots away thats one answer. But if it actually uses the sun to brake/slow down and course correct to head towards earth, thats the other answer. But from our perspective, its going to pass behind the sun so we wont be able to see what its doing until its already done it.
It isn’t really “going around” the sun. It makes a close approach to Mars, crosses a little inside Mars’ orbit, then heads on out of the solar system. It’s moving so fast, and will stay so far from the sun, that the sun’s gravity barely changes its trajectory.