Excommunication, especially a jure, is either latæ or ferendæ sententiæ. The first is incurred as soon as the offence is committed and by reason of the offence itself (eo ipso) without intervention of any ecclesiastical judge; it is recognized in the terms used by the legislator, for instance: “the culprit will be excommunicated at once, by the fact itself [statim, ipso facto]”. The second is indeed foreseen by the law as a penalty, but is inflicted on the culprit only by a judicial sentence; in other words, the delinquent is rather threatened than visited with the penalty, and incurs it only when the judge has summoned him before his tribunal, declared him guilty, and punished him according to the terms of the law. It is recognized when the law contains these or similar words: “under pain of excommunication”; “the culprit will be excommunicated”. Catholic encyclopedia
Certainly a case can and should be made for latæ excommunication. Just as for the rest of the CINOs who PUBLICLY advocate grave sins, i.e. abortion,
Under what canon?
The definition of heresy is EXTREMELY narrow. The one time I can think of that she broached it, she was resoundingly slapped down by multiple bishops...and hasn't repeated that kind of statement since.
The abortion canon requires the person to actually have an abortion or "procure" an abortion (e.g., perform it or pay for it).
Those are the only two that apply to latæ sententiæ excommunications. The ones I cited above require a trial (i.e., ferendæ sententiæ).
Canon 915 definitely applies. But Canon 915 is not the juridical punishment of excommunication (of course, we will leave aside the fact that the Archbishop of Washington won't even go that far, but that's a different issue altogether).