By which definition the first person crying "intolerance!" wins - now they can be intolerant for free, because they are just intolerating intolerance, but their opponents can't be. I don't think such model can be defined as "drawing a fine line" - more like providing a rich field for rhetorical abuse, as long as you can excuse your own intolerance by casting whoever you target as "intolerant" you yourself get a free pass for anything. Very convenient, of course, but to me it looks like a cheap trick.