This critique is one of rhetoric - which is not what McLuhan meant in the concept contained in that quote at all. Your complaint seems to be that the use of a

This critique is one of rhetoric - which is not what McLuhan meant in the concept contained in that quote at all. Your complaint seems to be that the use of a sexual metaphor affects the ethos of the speaker in the eyes of some. That metaphor is part of the message, regardless of whether or not you like it.