Briefly, the Earth's gravity alternately slows down and speeds up the asteroid in its orbit around the Sun. I don't know if they were quoting their source, or if they had written their own copy, but this is incorrect.
Gravity can only attract.
However, under certain circumstances, gravity can indirectly move an object further away. This is fundamentally different than repulsion, which implies a direct thrust away using only gravity. This is a relatively small nitpick, but represents sloppy definitions of words, and it doesn't help people to understand why this object behaves the way it does.