A "restricted" Robertson Tartan?

[figheadair]

However, mentioned in passing was a dust-up with a Robertson Clan Chieftan's "personal" tartan, but that was not elaborated upon.

Does anyone here know the story behind that? Nothing I could find on the Scottish Register of Tartans website provided a clue

I wonder if it was a reference to the Robertson with the white line that is sometimes (without authority) referred as 'the chief's sett'. It is worn by the current chief.