The problem is well explained, but what is the proposed solution?
a better look at what is defocused to try and determine the quickest way of getting close and determining actual focus.
there's really nothing they can do in silicon to resolve the issue, especially with big fast tele's...
A thought experiment, throw a 400mm F2.8 out of focus as much as possible. that's what your AF has to look at to determine focus. It's of course a hot soupy blurry mess. but from that the AF has to try to make an estimate. Thus why it racks in and out. but they are thinking of two speeds depending of what they call a reliability factor. Not really a solution, but perhaps better.
I haven't seen too many DPAF patent applications dealing with this, and of course, this is probably more a concern for Canon on an R1, etc camera, which they would expect to have the big fast tele's being used.
@Del Paso Macro is certainly another problem domain where out of focus can make it impossible to determine focus distance.