How much of a detour? I looked at the map and it looked like a couple of kms instead of 100m? I'd prefer to do the stairs than another few kms.
And the amount of cars who also use that estate to cut through is significant too. Should be fun when the Metro Tunnel works and compulsory land acquisition blocks one side of the estate's entrance/exit and takes out the street closest to the rail lines!
From the entrance to the corner of Childers/Kensington Rd, the Dynon Rd path is 2.2km vs 1.2km taking the direct and slightly naughty way. If you discover the gate is closed, then doing the U-turn and going back over Arden St bridge is 1.6km but you have to carry your bike up the stairs. If you have a really heavy bike, then the longer way is probably easier.