I have never heard this one. I find it hard to believe that Augustus would do anything positive for the soldiers of his enemy. Do the deniers of the settlement of Augustus' veterans (his side, not the enemy) have an explanation for the use of the chained crocodile better than the settlement of veterans? Full colony status with citizenship and a reference to a crocodile and palm is what you do for the soldiers that made you emperor.
The fundamental problem is with the theory of colonists to Nemausus being retired legionaries is that the city was already a colony with Latin rights as of 40 B.C. and became a colony with citizens rights in 28 B.C. Until I talked to some of the local historians at the museum in Nimes I too subscribed to that theory. When I did my research I could find no concrete evidence to support it. Agrippa had been governor of Trans Alpine Gaul and was a benefactor to the city I suspect that the reference is more general. Basically they found a way to honor a benefactor to the city and the man responsible for granting them full Roman citizenship and celebrating the campaign both of them are associated with.