Into other words, a "jet engine" for the fabric of space/time.
That's what the Franz Joseph nomenclature suggests, but that is not what an Alcubierre drive is. The concept behind the AD is that a black hole is generated in front of the ship and a white hole behind. This is not really "bootstrapping" the ship through space, where the ship "falls" toward the black hole. The idea is that a "bubble" of twisted space-time surrounds the ship. Thus, the ship is isolated in its own region of normal space, while the "bubble" acts as a kind of "lubricant," allowing the ship to do all kinds of FTL stunts without the time dilation penalty.
The whole notion of "space-time," twisted or not, sounds ludicrous to me. But if one grants that much, I don't see why this escape clause shouldn't work.