A big Rov in Monsey who knows the case said they can do this.
I can see the argument in favor of this. (The argument against this is obvious. Siblings can't be blamed for what members of their family do)
Many people who behave badly are enabled by the people that support them. They are not operating entirely independently. If you were to alienate the badly behaved individual from their entire support network, there is a solid chance that they will shape up.
Every sicko that I know has friends and family supporting them, and by extension, their bad behavior. I know a guy (a "frum yid") that ran a ponzi scheme taking hundreds of thousands of dollars from people and leaving them high and dry, never to pay them back. He used the money to fund himself a lavish lifestyle. Trips around the world, expensive apartments, expensive car leases etc. They begged and pleaded for their money back and he literally ignored them. Do you think this guy is totally alienated? Absolutely not. Do you think he stopped taking money from people and never paying back? Absolutely not. He continues to be enabled by his friends and family. They treat him like a good friend and a cool guy. He hosts Superbowl parties, Friday Night meals etc. These friends are his enablers. The only way I can ever see this guy shaping up is if he becomes completely shunned by his friends and family, and perhaps named and shamed publicly so that nobody gives him another dime.
Back to the case of the gett, calling out the family is essentially telling the family to turn on their sibling and alienate him, in the hopes of forcing him to give the gett. They should ignore his existence, and he will feel the pressure.
Based on what I see about this story in particular, his mother is clearly an enabler. She testified in court against the wife, and provides room and board to her son. She needs to be pressured to kick her son out of the house and stop providing for him financially until he gives the gett. He is an insane, delusional man who thinks his wife will "come back".
Just my 2 cents.