Sorry, I think that's kinda harsh.
We don't know, but all reports say Zahra adored her grandmother and her grandmother her. We also have the statements from people who knew Zahra during her medical treatments in Australia and were touched at how loving, caring, etc. the grandmother was. Grandma was raising her during the scariest, and yet happiest times of her little life.
Even wonderful people sometimes raise children whose crimes they cannot comprehend let alone defend. Parents whose children are involved in illigal activities, drugs, abuse, murder, coverup of murder and all the other things that we are speculating about AB have not necessarily done something to cause that. Once they are grown, the sad fact is, you still love em, but you may not like em or their actions. KWIM?
It would seem from the falling out that Grandma tried to convince AB that EB was bad news and tried to convince him to leave Zahra with her (the only mother figure this child had ever had from what we are told).
I think grandma gave AB some choice words and AB left OZ and left grandma there with no recourse and no Zahra. I also think he hasn't contacted his family from OZ so that he didn't have to hear them try to reason and plead with him or badmouth his new love.
I can't find anything so far to cause me to think Grandma is anything other than a traumatized grandmother who may blame herself. Why didn't I stop him? Why did I leave things the way I did? Maybe if I'd been held my tongue a bit I would at least get to talk to Zahra on the phone. Maybe I would have known she was in trouble.
I cannot imagine what it is like to be in this woman's shoes. I got nothing bad to say about her.