the problem with lawyers and "legal" interpretations is that they often forget why the clumsy wording exists in the first place.
the whole idea is that aircraft in near proximity to the runway, and in near proximity to each other, have altimeters showing the same basic information.
if you are trying to maintain 500ft vertical separation with one aircraft on a sub scale of 1013mb and the other on a sub scale of 1032mb both pilots may think that they are ok but in actual fact they are at the same altitude and will collide.
the rule is just trying to get aircraft to use the same altimetry settings at appropriate times. what is so hard about that that it comes down to some tommyrot about the meanings of "will" and "shall" ??