Well considering that the SN projectile is probably the size of about ten people, and we take into the consideration that it's at least condensed enough to stay together, it's probably spewing out somewhere around 1800 pounds of anti-matter. And given that:
Quote: A quantity as small as a kilogram of antimatter would release 1.8x1017 J (180 petajoules) of energy. Given that roughly half the energy will escape as non interacting neutrinos, that gives 90 petajoules of combined blast energy and EM radiation, or the rough equivalent of a 20 megaton thermonuclear bomb.
Oh yes. Antimatter just likes to hit matter and disappear. Indeed.
-Edit- Oh, and even if it were only five pounds, or even one (see above quote for results) that would still utterly destroy something. Not just eat a hole in the ground/ship and raid the surrounding area with radiation.