I do not know because I'm not american...However, I think it could be.
I think that we are prone to see Jack's mom as a loving and comforting figure.
However, she had probably sided up with John's all of her life. Of course, in the 60s-70s being a woman there, with a violent and omophobic husband and a gay son she loved so much had to be a nightmare so I do not blame her. She was probably going trough hell.
Probably she wanted them to bond. But how could she want him to bond with a husband who had pee on him (from the SS)?
Also, maybe it is another topics, did Ennis know how violent John was to Jack, physically and psychologically?
Did Jack ever tell him? How did he react?