Re: Now I get it
If they're inside Earth's orbit then whatever "jolts" them would have to speed them up to give them the energy to get any nearer to us.
Also, since this one, at any rate, has an orbit highly inclined to the plane of the ecliptic, whatever gives them the boost the increase their orbit (by a significant fraction of an AU) would also have to happen in exactly the right way to neatly pop it back into the ecliptic.
I reckon the probability of an interaction (probably with the same planet that knocked them out of the ecliptic in the first place) that boosts their kinetic energy enough, alters the plane of their orbit, and pushes them into a new orbit that crosses that of the Earth is so vanishingly small, it may as well be zero. I know million-to-one chances happen nine times out of ten, but the sorts of odds involved are going to make million-to-one chances look like a certainty.