Blue on blue
Having served on exchange with the US army as an IP, albeit some years ago, I can assert that they were very specific about vehicle recognition. They had their list of 40 or so vehicles that they had to know. furthermore they had some realy good flash cards of a number of other vehicles. The problem was that the only mandatory vehicles were those of US types and soviet block types. Most of the other stuff was "nice to know". As I recall this included all or the vast majority of Brit stuff. That may have changed but probably not, thus they owuldn't hve a clue what a scimitar looks like.
Neverthess, the ROE should be robust enough that all targets, particularly targets of oportunity, are identified as red prior to engagement. As previously mentioed the Aussies have not engaged targets unless certain. 90% certainty does not cut the mustard.