A 50. The rules are silent on this issue. Natural attacks, like a bite, don't really address "handedness", they merely reflect what can add 1/2, normal, or 1-1/2 times str to damage. The safest bet is to assume the mouthpick weapon is treated as whatever hand it should be, light, 1H, or 2H. You could also argue that a 1H should count as a 2H is it's the only weapon that creature uses, since bite attacks used when they are the only weapon get 1.5 Str. Either way, it's up to your DM.