If the head referee makes a call on field then upholds it on review

Isn’t that bias? In the frisco game just now Cleveland’s QB had an underhand toss that clearly looked like a fumble, but the head referee says it was an incomplete pass. Then he is the one who goes to review the play, of course he upholds the decision he made. Wouldn’t it be wise to have another official make the determination on the call? That way bias could be removed? The ball was clearly fumbled.