Why does Oneness deny Son as creator?

Originally Posted by Chan

Because the writer is referring to the Son in the present tense, to a point within time, and not to eternity. As "the Son," Jesus existed within time.

Yes but this Son, who's mentioned as the Son is said to have created the universe, so how can the Son be the creator and yet not exist before bethlehem? The text of hebrews 1:2 does say Son.