What the spook box says and what's inside are two completely different things, by design.

> If a US citizen needs to be spied on by the US government, the FBI is supposed to do that.

Semi-autonomous collections systems generally aren't capable of determining citizenship.

Once the data is at rest, much of it is made available to a surprisingly large number of federal and state agencies - and even local agencies via fusion centers, etc.

The system is built for dissemination. Within that, some checks on citizenship could be possible for some data. But even then, once a foreign person is part of the data/comms transaction, all the related data is available - citizenship of the other participants is no barrier.