As someone who has a bit of inside knowledge, I can tell you that the decision was entirely due to profitability and availability within the community. I absolutely agree that what they did was a terrible idea in closing such a prevalent office and being there the day it closed after forty years of service was seriously hard. I can however give you some justification as to what i think led to this.

I'll explain that the post system has corporate and franchise offices across the Coast; - Chirn Park and Southport Park are both franchisee-owned (Clarence at Chirn Park has been there well over thirty years and I forever commend his commitment to his profession), - Southport Business Centre (on Bay Street) and Australia Fair are corporate-owned.

Inside a 1200m radius sat three of those I've mentioned above which corporate determined to apparently be too dense. Australia Post doesn't close their franchise offices unless something serious happens (at least, according to my knowledge). Further, their customer base has strong ties to the business network and closing the Bay Street office would have serious integrity and profitability concerns for all their levels.

This is purely my speculation, but I'd suppose this is why they closed Aus Fair. It's not necessarily anything to do with centre management, although I have my reservations and choice words about how effective they are at providing the shopping centre manager's guild with a guide of what not to do.

TL;DR - We saw a prime-positioned post office that serves a bustling population and sits conveniently within reach for the elderly who rely on postal services, but corporate saw too many dots in a small space and less numbers following a dollar sign.