I couldn't find any trace of the abortion remark other than allusions to it in various comments sections, none preceding an unsourced and unattributed comment from 2007. So, I was skeptical of the quote's provenance ("Apocrypha until proven otherwise"). I updated the post this morning to reflect a more specific attribution pending confirmation, and have now been beaten to the NYPL's microfiche room by longtime lead Voice critic and keeper of the institutional memory J. Hoberman, who has found the quote in question. It's pictured; it's from White's 1998 review of Baumbach's film Mr. Jealousy. It's pictured, complete with the last lines:
I won't comment on Baumbach's deliberate, onscreen references to his former film-reviewer mother except to note how her colleagues now shamelessly bestow reviews as belated nursery presents. To others, Mr. Jealousy might suggest retroactive abortion.
(The "onscreen references" to Baumbach's mother Georgia Brown are on the marquee of Cinema Village, mocked-up for a Man Who Shot Liberty Valance revival featuring pullquote from "G Brown.")
That, then, is what people were talking about.
So ends my 24 hours spent inadvertently fanning flames that well precede me. Always glad to help, guys.