The fact that the government is moving to collect these data as well as partner with third-party private industry (e.g., Palantir) to avoid direct data collection that runs counter to current/settled law, you have to begin to piece together the future.
Regardless of your apparent desire to avoid accountability for the US government's actions, potential or actual, these are truths for which the citizenry need to protect themselves against both by their own individual actions as well as the collective actions of their voting behaviors.
In other words, the people who put their DNA up help track down dangerous criminals. This doesn't sound like something people would object to. I certainly wouldn't.
And this is not the discrimination we were talking about, unless we have now defined the tracking down of murderers and rapists as "discrimination".