Horizontal Exit and S-2 Open Garage Exit Stair

[Noob]

This is an odd one: two separate sprinklered buildings abutting each other, an S-2 Open Garage and an R-2 apartment building. R-2 is 4-Stories and S-2 is 5 Tiers. Would like to use one of the S-2 exit stairways as an exit access stairway for the R-2 building. I would like to keep that stairway not enclosed per IBC 1019.3, exception 6, which has this little caveat at the end regarding "stairs serving only the parking garage". If I’m using a horizontal exit to "exit" from the R-2 building into the S-2 building through my 2-hour fire separation, I shouldn't need to enclose the exit access stairway in the open garage, correct? My logic is that the horizontal exit is an actual exit from one building into another completely separate building. So you travel from the R-2 Exit and back into the S-2 Exit Access, and thus the stair is only "serving" the S-2 Exit Access. make sense?

 

[Noob]

Adding because I've done a little further thinking. I think this can probably only be answered by an AHJ. Maybe I'm rationalizing the code too heavily, but I could see how this would make sense in a condition where you have an open parking garage UNDER an apartment building and you are trying to stack the exit/exit access stairs. Because you'd be traveling from an upper floor to a unenclosed stairwell at the parking garage level - obviously not continuing the shaft all the way down to the ground from a different use above is a hazard.