I agree. Dr. J will need to provide a definitive ruling on this (at least we won't have a 5-4 split !!!).
For my part, I only count food, water, & fuel (if i'm carrying any & not eating just GORP - however, I count 1 esbit for emergency even when eating just GORP on a trek), but all of the others items you list (e.g., water purification/filtration, chems, Rx, TP, etc.) I count towards base pack wt.
But..hey...maybe it's just me that does that?