Sorry, I interpreted that as you saying Air pistols up to 6ft lbs m/e are NOT classed as firearms... cos, you said Air pistols up to 6ft lbs m/e are NOT classed as firearms
Sect 5 draws in what is covered in it's section. Things don't apply to it unless they're stated in it. Things that don't apply to the rest of the act are exempt under the rules. Section 5 explicitly mentions air pistols/rifles (i hate the word weapon), so clearly any air pistol/rifle is still considered subject to it, and this we know.
There's no wriggle on this. Experts, ie the HO, have stated their case. I don't think that's someone unqualified to do so either. The CPS guidance is just that. The HO states that it doesn't change the law, and that all it means is they won't prosecute. It doesn't mean they won't confiscate, which is what has happened.