Of course we don't know any of those details, but I think that ignorance does not reduce the strength and plausibility of Mommsen's suggested explanation. As I wrote, a study of the percentage of Antony's legionary denarii in second century hoards arranged by burial date might either confirm or weaken Mommsen's idea. A strong point against it, so obvious that I didn't bother to mention it above, would be the discovery of a legionary denarius of Mark Antony restored by Trajan!