First, Hemos and everyone else saying the same thing, the question isn't whether one can open Word files -- RMS's point is that we should discourage the use of .doc, or free software developers will be perpetually chasing Microsoft's newest version.
That said, Stallman is proposing a particularly counterproductive way to go about it. When I receive a file I can't open, I send a polite message to the effect of, "I can't read that file format. Please save the file in RTF format (Select "Save As.." from the File menu, and then choose Rich Text) and resend it. In the future, please send me files that way, so I'll be able to open them right away."
That has the advantages of a) not confusing the secretary or supplier who doesn't even know that there are different file formats with some political rant about Kenya, the Microsoft monopoly, bytes and freedom, b) doesn't convince a more knowledgeable recipient that Linux users are rabid, socially dysfunctional loons and c) is the way a decent human being behaves.
Richard Stallman probably doesn't realize that when the rest of us receive a Word attachment, it's not from a reporter seeking our views on Free Software and appreciating his tantrums as a little added color for his article, it's from a coworker just doing what any normal computer user does.