Medical concerns are valid,especially mtDNA, but I doubt that the info we post or see on the web is of any use. The problem comes with the testing companies sharing their info with their partners. They all state that they don't sell to third parties, but a business partner is not a third party, and neither is a grantor for non profits.
And there is this as regards the police: https://www.legalgenealogist.com/2015/02/08/privacy-the-police-and-dna/ Excerpt quote:
"So when that cousin asks you, once again, whether his genetic genealogy test can be used by the police, remind him, once again, that the police don’t particularly want it — and they don’t need it.
First, the tests we take for genealogy aren’t all that useful to the police. Our tests tell us how we are like other people — other family members who share common ancestors with us. The CODIS markers focus on parts of the DNA that make us unlike other people and set us apart as individuals.
And, second, if the police want our DNA, they will get it.
Even if we say no."