I think Stan's post was maybe too simplistic and provocative, but his point seems a legitimate one for consideration. Actually (and Stan can chime in here and correct me otherwise), he seems to have two points:
I think you are giving Stan way too much credit for your own thoughts on the subject. If he had articulated anything remotely on the level you are suggesting that would be different.
I don't know what an average aikidoka is but I am not losing any sleep over meeting other martial artists with the equivalent level of experience in some other martial art in a street confrontation. First, the number with over ten years experience in one art is not enough to make it even remotely likely. Second, I have had the experience of holding my own against someone of another martial art and I have seen my teacher hand someone their lunch so to speak on a number of occasions.
That's different discussion altogether than the cartoon Stan was drawing.