Is A Bulk Feed Allowed in Interior Exit Stair?

Do you have any thoughts or input on the interior exit stair penetration limitations of Section 1023.5 of the IBC? 

I have someone contending that you aren’t allowed to run a “bulk feed” main into a stairtower and then back out again on a different level.  They claim that 1023.5 limits penetrations only to MEP equipment that serves the stairwell itself.  I contend that, especially as clarified in the 2018 edition (although I contend that it was always the intent), any fire protection system is allowed to penetrate such a stairtower as needed, as long as the penetrations are correctly firestopped etc…
 
The confusion comes from the 2015 edition, which reads (emphasis added to indicate the confusion that I think this person is having):

“Penetrations into or through interior exit stairways and ramps are prohibited except for equipment and ductwork necessary for independent ventilation or pressurization, sprinkler piping, standpipes, electrical raceway for fire department communication systems and electrical race-way serving the interior exit stairway and ramp and terminating at a steel box not exceeding 16 square inches.  Such penetrations shall be protected in accordance with Section 714.  There shall not be penetrations or communication openings, whether protected or not, between adjacent interior exit stairways and ramps.”
 
I believe that that person is seeing that “serving the interior exit stairway and ramp” portion of that snippet, and they are applying it to everything.  However, I contend that that is actually applying specifically to “…and electrical race-way serving the interior exit stairway and ramp and terminating at a steel box not exceeding 16 square inches”.  I think that the person is cherry picking what they want it to say, although it is somewhat confusing the way it’s all written on one line.  I believe that if that person really wanted to apply this verbatim, then you would not even be allowed to have combined standpipes that feed sprinkler systems outside the stairwell, or even dedicated sprinkler risers in the stairwell wouldn’t be allowed to serve any floor area outside the stairwell.  Basically any sprinkler riser in a stairwell would only be allowed to feed that specific stairwell…  I think it’s clear that this is not the intent of the code.

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I believe that the 2018 edition (and commentary) clarifies it much better, especially when paired with the IBC definition and commentary of a fire protection system:
 
1023.5 Penetrations. Penetrations into or through interior exit stairways and ramps are prohibited except for the following:
1.Equipment and ductwork necessary for independent ventilation or pressurization
2.Fire protection systems. [see definition]
3.Security systems.
4.Two-way communication systems.
5.Electrical raceway for fire department communication systems.
6.Electrical raceway serving the interior exit stairway and ramp and terminating at a steel box not exceeding 16 square inches.
…
[F] Fire Protection System. Approved devices, equipment and systems or combinations of systems used to detect a fire, activate an alarm, extinguish or control a fire, control or manage smoke and products of a fire or any combination thereof.

• [Commentary] A fire protection system is any approved device or equipment, used singly or in combination, manually or automatically, that is intended to detect a fire, notify the building occupants of a fire or suppress the fire.  Fire protection systems include fire suppression systems, standpipe systems, fire alarm systems, fire detection systems, smoke control systems and smoke vents.  All fire protection systems must be approved by the fire code official and tested in accordance with the referenced standards and Section 901.6

 
I believe that the restructuring of 1023.5, inclusion of defined “fire protection systems” as 1023.5(2), and the accompanying definition and commentary of “fire protection system” make it clear that any valid fire protection piping (including “bulk feed” piping) can penetrate a stairtower as necessary, and need not specifically only serve that stairtower.  Some very common and non-exhaustive examples of this scenario would include:

1. Sprinkler risers in stairtowers that feed systems outside of the stairtower.
2. Combined standpipes in stairtowers that feed sprinkler systems outside of the stairtower.
3. Standpipes that branch out of a stairtower and feed additional 2-1/2” hose valves spaced throughout a floor when maximum travel distances of NFPA 14 can’t be met with stairtower hose valves alone.
4. Standpipes that run the full height of a stairtower and then penetrate through the roof of that stairtower in order to put a “roof hydrant” on the roof.

 
Do you have any thoughts on the subject? 

I know for sure that I have had scenarios throughout my career where we have had a fire pump on a lower level (or basement, or sub basement) that only has a single stairtower down into it, and we have run “bulk feed” piping up to a more “common” floor where we in turn branch out and interconnect all additional standpipes.  I contend that this is perfectly acceptable as long as the valves are arranged correctly such that you can isolate the individual standpipes without also affecting the bulk feed to all other standpipes.  In other words, in whatever stairtower you were vertically running the bulk feed, the standpipe would have to be a separate vertical pipe so that you could isolate it off with a control valve, while still allowing the bulk feed itself to continue to carry water to all other standpipes in the building.  You couldn’t combine the standpipe and the bulk feed in that one stairtower, or there’d be no way to isolate that standpipe without affecting all others.