>I've read if not shelf-meters then certainly shelf-decimeters of SF with plenty of marines in them, none being of the Warhammer variety.

I've read at least a shelf-meter of books involving 40K space marines. As the article alludes, 40K space marines are called Adeptus Astartes or simply Astartes.

This is one of things that makes this such a jackass move. Their own, licensed writing would seem to acknowledge "space marine" as generic.