But law enforcement is not using the encoded information, they are just taking a unique pattern from the information and using it for identification purposes.
I could for sure envision a situation where they use the encoded information. Let's say they find that the sample comes from a person who is predisposed to a heart condition and they already have a description putting him in the 40-50 age range. That's a pretty significant piece of information that can help narrow down a search or canvass, especially if there's any other meta data they can correlate to the crime.
No, I would not consider it unreasonable but a lot of people probably would. And I don't know enough about inferring future health conditions from DNA alone, but I meant it as an example for a future possibility. If anyone does know, exactly, what you can infer from DNA alone and how that would be extremely helpful.