Well I read this as brooch as in an ornamental pin (generic) and not necessarily as a Plaid Brooch. I prefer brooches in that definition to the usual sword shaped kilt pins. In my mind the XMarks kilt pin is more of a brooch along with the malt glass kilt pin from kiltgoodies.com.

I would never use a plaid brooch as a kilt pin. My aprons would scream when a pin that large went through.