Okay, I'm just a newbie thinking out loud here; I'm sure knowledgeable people will be along in a moment. It seems to me that since (as I understand it) the main point of this is to get the plant to use up the nutrients it has to get them out, this is the one time that nutrient lockout is not only NOT something to avoid, but something that would actually help. So it seems to me that, at this point, the worse the pH, the better.
But honestly, you'd be a fool to listen to me without any back up from people who know wtf they're talking about!