It's not from a satellite, it's through the cell network.

As for the flight attendant thing, lots of people leave their dongles attached to their notebooks. Also, the author discusses using the MiFi while waiting on the runway for take-off.

Given all that, the plane use case does seem pretty weak, though.

That was my thought as well, but later in the article he mentions using the MiFi in a plane parked at the gate. I still think it's silly to worry about a USB modem being "snapped off".