The assessor deliberately skips over the failure to "invite the keeper to pay the unpaid parking charges".
They skip over this because it is not possible to rebut your appeal point and they are keen to find in the operators favour.
We've seen this before where the assessor deliberately doctors your appeal point in order to provide a rebuttal.
POPLA have promised that they were tightening up on assessors training on PoFA compliance.
You should now write a complaint and submit to POPLA - make the complaint purely on the basis that keeper liability was wrongly established and that paragraph 9(2)(e) was not complied with.
I can scribble an complaint if that would help?