I'm sorry to hear about your father and how he was treated by the JW's. When I was an elder the treatment most likley would have been the same because of the arrogance that prevails among JW elders. Just as the WT teaches them, by example, they will feel a false sense of indignance at reading a letter such as yours. Although most here will fully understand that type of treatment is common among JW's it's difficult for outsiders to comprehend a religious organization could act so cold and uncarring. In a time of need they abandoned your father because of man made rules and a forced association upon percieved "strong ones" all others can fall by the wayside.
I can remember a WT magazine article along the lines of, Jehovah's Chariot, that was constantly on the move. If you were not following or keeping up it just kept on going and did not look back. I think if any had the misfortune of being in the way it would run them over and also not look back. So the teachings and foundation of the WT is callous to the core and is hardened further with any criticism. The harder they get the easier will they crack.
HCM