You might be stuck with this one just based on how section 42 is worded.
Railway crossing
42
(1)
For the purposes of this section a railway train is approaching a railway crossing if
(a) a clearly visible electrical or mechanical signal device
gives warning of the approach of a railway train,
(b) a crossing gate is lowered or a flagperson is giving a
signal of the approach or passage of a railway train,
(c) a railway train
(i) is within approximately 500 metres of the crossing,
(ii) is approaching the crossing, and
(iii) either sounds an audible signal or is visible,
or
(d) a railway train is visible and approaching the crossing and
by reason of its speed or nearness is an immediate hazard.
(2)
Where a railway train is approaching a railway crossing, a
person driving a vehicle that is approaching the railway crossing
(a) shall stop the vehicle no closer than 5 metres back from
the nearest rail of the railway, and
(b) shall not proceed to drive the vehicle across the railway
crossing until the train has passed by the railway crossing
He probably wrote the ticket for 42(2)(a) or (b) and it just looks like (0). His argument will be that 42(1)(a) or (c) is applicable due to the approaching train and the signal being activated and therefore you were violating either 42(2)(a) and/or (b)