You have to remember who the POLPA paymasters are.
Donald Rumsfeld, "Clarity is exactly what we are trying to avoid."
The POPLA response is deliberately incoherent as they don't want to provide specific details on the reasoning behind the parking operator's decision to pull out of the case.
This behaviour has a multitude of advantages from their perspective.
Mainly, POPLA can never be accused of being in receipt (and subsequent acknowledgement) of 'facts' which might have a bearing on future cases - take this case as an example - what happens if they get an appeal for the same location tomorrow? If POPLA acknowledged (or were even made aware) that the location is in fact a public road then they'd have to find against the parking operator again and again.
So they are EXTEREMLY careful to ensure that each and every case is kept strictly as an individual stand alone case - that way the parking operator can carry on dishing out dodgy PCNs in the knowledge that a large percentage of them will continued to get paid by unsuspecting motorists.