The bill of rights was written long before germ theory, and the courts have so far proven incapable of understanding the problem of probabilistic risks with the standard of "clear and present danger".
And just because something is legal, doesn't make it right.
For your second point: there's a long history of states using police to the detriment of their citizens (And, in my opinion, they continue to do so, even to this day), so we should abolish the institution tomorrow. How's that for an esoteric theory? For some reason, though, the courts aren't super keen on that line of reasoning...