Ethicalconundrum is correct on several points.
1. In the US, government agencies have no "rights". Only people have rights and various laws give government the power to infringe/regulate those rights.
2. One of the rights people have is the right to privacy and the right to property (be secure in their person and their property.) The government may only infringe on that right with a warrant issued by a judge. This law is alleged to give the government the power to intercept the signals from a private UAV without a warrant, infringing on the owners right to privacy.
3. Another right people have is the right to be compensated for any "taking" by the government. The government may seize or destroy private property, but only after due process, and even then must reimburse the owner of that property its fair market value. This law is alleged to give the government the power to destroy or take a private drone without due process and without reimbursing the owner.
4. Private citizens are not currently prohibited from intercepting the signals of a private drone nor prohibited from downing a private drone. However, they could be prosecuted for unlawful discharge if a firearm was used to down the drone. And regardless of what method was used to down a drone, the owner of the drone can sue the person who downed the drone in court for damages related to the downing. Of course they would have to prove the defendant actually downed the drone and had no right to do so.