In articles about him, I see that it appears that many of the people who complained about his insensitivity were not, themselves, members of the groups who were the targets of his barbs. I have a suspicion that this is frequently true of those who rush to the rescue of the offended.
Callahan apparently held a pen in one hand, then held that with the other, and used his shoulders to move the pen around. In addition to being a paraplegic at age 21, he stopped drinking about age 26. (I gotta learn to stop whining.)
So long, Johnny. I wish I had known you better. I will seek to do so through your work, now.