Well yes, whilst the defense needs to justify his/her position (not unlike self defence) it's not technically true that the onus is on the defense to prove his/her innocence. For a court to convict on a Goods in custody charge, the presiding magistrate must be satisfied that he/she reasonably suspects the goods to have been obtained unlawfully. The suspicion must also be attached to the goods not the person and the arresting officers opinion is irrelevant the opinion of the court at the time of the hearing is what that suspicion is based on.
For the court to conclude there is reasonable suspicion the goods were illegally obtained that conclusion must contain some probative value. The defendant having form (previous convictions of GIC) is sufficient to satisfy the search without warrant test but not the GIC charges.
The onus in on the prosecution in any criminal proceedings. This is no different in a matter of Goods in Custody.
Like someone else said, not enough information here but either the guy gave the police reason to suspect the bullion was illegally obtained. ie the guy was being evasive about the circumstances of why he had it or where he got it from, or the police officers were incompetent (which isn't unlikely) but if he just purchased it he would be able to substantiate the purchase, receipts or notthere is more to this case that meets the eye.
