There's a bit of scaremongering in the headline; these are being tested domestically by the DOD use outside of the US. The DOD isn't allowed to conduct domestic surveillance.
They parked a visible radar blimp over I95 outside of Baltimore and operated it for a couple of years. What’s the difference between “test” and “really using it” when the tests last that long?
There are many loopholes for domestic stuff too. A National Guard member controlling the thing for example.
And we did use these blimps in Afghanistan. Very apt and chilling definition.