pretty bold claim -- as with any additional justice element the innocent will be trampled to some degree.
Here's the thing : it doesn't just open up criminals for prosecution, it also opens up the 23andme population to an even larger arrangement of possibilities for self-incrimination and 'incorrect or misdirected pursuits of justice'.
It's nice that a well known murderer was found out, but the reality of the situation is that we likely wouldn't hear very loudly the stories of innocent folks with cases mishandled by a law enforcement bureaus that were enabled by 23andme or similar services. It looks bad on the law enforcement agencies and it looks bad for the corporation.