One would think that light is also limited to line of sight (almost by definition - I mean, I generaly use light for my sight; if some BBS members don't, then empeg has spread *really* far )

This smartassing about light, IR and RF being the same (i.e. EM radiation) is just the guy's way of saying 'oops!'. (BTW, 'Radio Frequency' - as opposed to, say, visible frequency - means exactly that - a portion of EM spectrum FCC wants to control )