Let's be honest... UTR
Moorabbin is a private airfield after all and they can do what they want!
Exactly the same as Essendon and Bankstown they still have a gate with a pin number on it that you read when you leave, then type in again to get back in again.
I'm sure I'd be suffering the same problems if I went up north to your field no doubt.
They are doing their best to make it easy for everyone given the new requirements.
Swiping or passing a credit card on the gate is a fair and reasonable method of gaining access to public areas thus allowing re-entry to airside. Better that than having to have a specific airside pass.