Can I do an Exception to Policy (ETP) to waive Warrant Officer Basic Course?

I think you are misreading tihis:

(1) Enlisted applicants in the grade of E8 or E9 who are certified by the DA MOS Proponent prior to the date of initial appointment (attendance at WOBC is not required) may be appointed in the rank of CW2 upon completion of WOCS. Constructive credit for WOCS may be granted if the Soldier has satisfactorily completed OCS within the previous five-years.
(2) Enlisted applicants in the grade of E8 or E9 who are eligible for DA MOS Proponent training may be
promoted to CW2 upon completion of WOCS and WOBC. Constructive credit for WOCS may be granted if the Soldier satisfactorily completed an OCS within the previous five-years. The following Statement should be placed on the NGB Form 89 (Proceedings of a Federal Recognition Examining Board) for appointment: “Applicant is a pay grade E8 or E9, upon completion of WOCS, is eligible for appointment as a WO1. Upon successful completion of WOBC, applicant may be promoted to CW2; effective the day following graduation.” The effective date will be no earlier than the day following graduation.

In context, this really means that if your packet was written up the right way, you could have been appointed CW2 upon completion of WOCS, instead of needing to wait until WOBC graduation to be appointed CW2.
But either way, you go to WOBC.