I believe that assuming new capabilities will be used in a particular way has historically proven unreliable. The United States already has broad tracking capability and has not yet used it to stifle dissent (at least, not systematically). What justifies your belief that slightly broader monitoring capability will be used in that fashion?
I don't know that there's any evidence that says directly it will be. What I believe is that the country is becoming less free as time goes on and I think that means at some point they will use the data for dissent stifling. I don't think they need to now because the bread and circuses are good enough.