I don't think omega is a perfect predictor or benevolent. (edit : or neutral/'not malevolent'. he may well be malevolent, but a million dollars is a million dollars. :-)

Omega doesn't lie and is very powerful and smart. Sometimes he predicts wrongly. He only says something will happen if he is certain in his prediction. If he is at all uncertain, he will say he predicted. (he may also say he predicted when he is certain, as that is true.