My house, currently in construction, is designed with the stairwell in the corner of the house.  On the entry level, there will be a small closet located under a portion of the stairs, but the other half backing up to the exterior corner walls will be inaccessible due to low height (see attachment).

I’m guessing my GC plans to finish the interior of the closet with drywall and leave the studs in the inaccessible area insulated (dense pack fiberglass BIBS) but not covered with drywall.

Is the general guidance in this community to drywall and tape those exterior walls in the inaccessible area as part of the general air sealing effort? It seems to me this is necessary to help contain any air leaks that might exist in that corner.

If we drywall the inaccessible area and finish the closet with drywall, do I need to be concerned about that dead airspace behind the closet and under the stairs?  Would l need some kind of air transfer grille between the closet and the dead space, or will the stairs leak enough air to prevent any problems from developing in that corner?