The supreme court ruled, that abortion is protected by the consitution with Roe v Wade. So there was no need to pass protection for it. Biden was unable since Congress is Republican.
They could have totally done it in previous administrations, during Obama's majority. Biden could have written an executive order, and even if it was challenged by the Supreme Court, at least we could say he tried. No excuses.
Under Obama Row v. Wade was still standing. Biden needs to pass a law to make Roe v. Wade an actual law. Executive orders are just that orders to the executive. They would be struck down by a temporary ruling right away, as it is just outside the power of an executive order.