Ask him what family business really means not the WT interpretation. Isn't Health, education, marriage, divorce, grandchildren, financial issues family business? At least in the real world.
The only problem with that is I recall one of the last circuit assemblies I went to a bethel speaker said (paraphrased to the best of my memory): "The governing body gave us some consideration with regards talking to disfellowshipped family members realizing that we might need to attend to necessary family business at times. Many brothers and sisters take advantage of this categorizing normal conversation as 'necessarily family business.' The slave provided this provision as a courtesy but it isn't anywhere in the bible. Ultimately it's your relationship that is at stake with Jehovah and you should think hard about any contact you have with DF'd family." In more or less words he said it could be the GB was overstepping in providing that. He was trying to inspire fear.
I don't know if they heard that talk or not, or if this admonition is endemic in the org. I don't know how open he'd be to redefining that definition. Worth a try perhaps.