Occam’s Razor - not necessarily true - sometimes the more complex answer is closer to the truth, given the billions of billions of galaxies in the observed Universe - not to mention the 300,000,000 stars in our galaxy alone.
Rocks do not adopt a perfect course to complete a perfect slingshot maneuver (to pick up speed to its next destination), passing unscathed through the solar system and around the sun except by amazing coincidence ... if you believe in them.
I doubt that it was a “slingshot” maneuver. Any object passing the sun will be attracted, and gain kinetic energy as it falls towards the sun, and give it back on the way out. Whether or not it gains angular momentum depends on the object’s trajectory. It is about as likely to gain as to lose kinetic energy.