You've agreed to one more month before deploying a BD (still think this approach is wrong), make that a month where you go no where near his cave. Keep as big a distance as you can between you and your H, no crumbs, no nothing (sorry Azzork). If you get some movement from him, leave a mere morsel nothing more, be very frugal, to encourage more, but if you leave nothing you'll get more movement anyway IF he's ready to talk. Fight any instinct to reach out or fix him and he may turn around but if you don't give him space he'll stick where he is, almost guaranteed.
As for the one month, I agree on some level. But I think one month of seriously doing some work and tracking the progress is better than giving up today and BD/filing.
As for doing "nothing" by his cave, I inderstand what you mean on some level. On an emotional level I DEFINITELY agree. No R talk, no deep convos. But I do think doing things to reinforce his positive behaviors is important. Being appreciative, validating, etc. I'm not suggesting she walk by his computer room in her underwear.
Take a look at some of the goals I listed on the last page. I mentioned I'm not great at it. Add stuff!!