Yup, you're right it's not a true A5 military scope...
He does side step it though by saying Winchester A5 Telescopic sight as used by Britishand Commonwealth snipers during the Great War.
It implies that it's similar "as used", so I guess he's partly honest.
Compare it against the example in the MKLas to what it should look like...
1916 ShtLE (Short Lee-Enfield) No.1 MkIII* Sniper Rifle c/w Winchester A5 (5 Power) Offset Scope
(Mfg by RSAF Enfield)
Regards,
Badger