Several nit picks.
1) You have seriously over stated the density of neutronium. A teaspoon of neutronium would mass about 100 million (10^8 ) metric tons. That's a lot, but still several orders of magnitude short of the mass of the Earth (6x10^21 metric tons).
2) It is unlikely that such a a small amount of neutronium could maintain its degenerate state and it would expand back to a more normal state. If my back-of-the-envelope calculations are correct, a chunk of neutronium the mass of the Earth (assuming it could exist) would be about 80 meters across.
3) Such a collision would shatter the Earth.

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson