If that's your only concern, you need to read up on something called "Nazis." Imagine what they would do with a database of genetic information.
No need for careful analysis, just force the company to give you a list of registered users matching some criteria. Your kill list is just a SQL query away.
"makes no screwing possible that wasn’t already"
Sure, but it makes it easier and faster to select targets for your screwing.
Sure, now they can start hating on people who have the gene that makes Cilantro taste like soap, but a lot of genetic things are already visible so I don't see this as being fundamentally different.
So place your data like your railways, where you can blow em up when circumstances necessitate it.