The flag should be called anonymous instead of "anon". In general the platform does not contain abbreviations, and the attribute value this models is also anonymous (crossorigin=anonymous).
Note that even the spec calls the thing this toggles the "anonymous flag" everywhere increasing the confusion.
Note also that the way Gecko has implemented this does not nullify Origin and omit Referer.
Sorry about the delay.
I guess the issue about Referer/Origin can be sorted separately at some point.