You do realise that every major footy Club of every code will be counting members this way within the next 2 years?At least the Eels reaching 40k would be genuine and not include pets and dead people and anyone that has walked through Redfern unlike Souffs numbers.
It is clever marketing and raises easy dollars.
Collingwood AFL counts 70000 members, a sizable proportion of whom are members because they bought a jersey and signed as a member at no extra cost at the same time as part of the deal.
Souths counting pets is no different to many other clever and innovative Clubs.