Actually, the opposite. Just because the person being "spoken" to doesn't understand, doesn't mean that the person who is "speaking" isn't communicating. That person would still be communicating, just in a way that the person being "spoken" to doesn't understand.
vs
The Body Language is still being "transmitted", but only someone with a visual sensor could receive it, unless physical contact were being made.
Well, you went further on to say that you judged this type of communication to be "visual" because it was dependent on the receivers senses AND (quote) "if you don't have eyes, body language doesn't matter." That says to me that the transmitter is irrelevant for the purposes of categorisation. If you had stopped off before making that interpretation, I would have likely agreed with you. But you made this assertion, denying poster's opinions that body language was different to talking and writing, because of the way it is encoded and transmitted - regardless of whether the receiver received it and understood it. Your saying, no, body language only matters as communication, because it is received in this way - denying it was anything to do with the transmitters unique efforts and methods (as per the question). BASICALLY, my qualm is that "humans communicate visually" is too broad a category to mean anything. You are basically lumping together writing, pictures, kinesics and body language in one category, although their METHODS (as per the question) are distinctly unique. The boundaries of uniqueness have blurred into over generalisation, if we were to follow your categorisation.