It is not clear what your criticism of the study is. Instead, you come across as ranting against findings that conflict with your personal values.
As far as I can tell from reading the summary of the study, it does not advocate that being married with children is a better or "the only right way" for founding a business. It just states observations. If you have evidence that the study is biased or made up, please tell us.
I believe you're overreacting, this has nothing to do with social mores or whatever, it would be the same as saying that close to 95% of these founders are straight and concluding that non-straight people cannot open a new business, this is not a good way to read the data.
If in addition to these 60% that are married and have children and some more 10% that are married but without children I would not say it's pointless. It shows a tendency which we could try to search for a cause.
If you see the link the industries cited depends on individual who have good skills and some years of professional experience in the same industry to be managed, this probably means this kind of person just matches the above pattern for founders, meaning that if you define successful founders in the cited industries the same way the researchers did you find probably something not distant from what they found. Just that.
As far as I can tell from reading the summary of the study, it does not advocate that being married with children is a better or "the only right way" for founding a business. It just states observations. If you have evidence that the study is biased or made up, please tell us.