indeed, because the Soulbow doesn't actually have a bow per say, but chooses a +1 enhancement to apply to every arrow he shoots. Like Lucky. It's only 1 re-roll per shot, but that's still re-rolling every missed hit once. Horribly, horribly munchkinly, but by strict RAW, it is legal.
Granted, even without Luckycheese, the Soulbow is a fantastic class simply for the fact that it makes the Soulknife not garbage.