I went ahead with 16 minutes, agitation every 5 minutes. The roll is junk, and development had nothing to do with it. I thought there was Tri-X in there, and I'm not averse to underexposing that by a stop if I need to, so Acros didn't stand a chance. There may be one or two salvageable images.
Moral: Don't underexpose your film by 2 stops+ stops.