Ohhh I misunderstood; I thought they were stealing data by simply observing the blinking LED, not that they had infiltrated the computer and were controlling the LED.
Allmost (or all?) of those attacks are only possible, if the target computer is infected.
And the scenario is that the virus wants to send data out, to a nearby decice which is also infected.
The term "exfiltrate" implies that the data is being "pushed" or otherwise sent outward from the machine, as opposed to being harvested from the outside.
