Lo Cascio believes that the portion of this passage on the crime of refusing a coin goes back to Sulla like the rest (p. 161). And, that originally it would have been something like the mark of the state, rather than the face of the emperor. Heinrichs thinks that it this regulation goes back to Marcus Gratidianus and that it is key for understanding the problem he was trying to address, that is according to Heinrichs: underweight coins whose value depended on their relationship to the Roman pound (esp. p. 267). [If I’ve understood the German properly!]
Given my current obsession with seals, I’m also rather taken with how the same law that covers counterfeiting coins also applies to false seals.