Earlier quoted context omitted.
If they file for bankruptcy, they cannot legally destroy the data. The data is a salable asset, the law requires them to preserve it so that it can be sold and the money returned to creditors. And many of the promises they have given about it's use can and will be broken by the trustees dissolving the company. The thing you need to consider when you give data to a company is not "will these people misuse this", but "…
My mom, dad and sister have all done 23andMe, so it doesn't matter if I have or not. They have an entirely complete genome for me. I agree with your limited license idea. It's just not ok that something like that can be dischargeable in bankruptcy. We don't have the ability to refuse consent in the first place, if our family provide it.
But where your parents have different SNPs, there's no way to derive which of them you inherited. What you said is a bit like saying that, because you know all of the cards in a deck of playing cards, you know what hand someone is holding, except in a counterfactual world where there are 10,000 possible cards and you know that a deck only has 52 of them.