The "current-limiting" of the alternator is due to the inductance of the stator winding.  If the alternator is connected to any constant-voltage device (a battery or even a dead short to ground) and given full exitation of the field the current will rise as the rpm goes up, but eventually the inductance of the stator windings will generate enough back-emf to limit the current.  A further increase of the rpm will not produce any more current.  It's not because there is a loss from internal resistance or anything.  Even overdriving the stator windings won't do anything as the iron saturates at a stator current that is not far from the max normal current.  The point is that as long as the output is connected to a constant-voltage load the output current will be limited to a value close to the current rating of the alternator.  So what happens if the battery becomes disconnected?  As long as all of your expensive electronics are on the battery side of the fault there is no problem, even though the alternator itself is subjected to a very high voltage.  What happens when it is reconnected?  Good question, but I don't think the system will be exposed to the full voltage because as soon as there is current in the system the voltage will drop, but I haven't looked at this particular scenario.  If for any reason the alternator stator becomes disconnected from the system it might be best to leave it disconnected.  That's one reason I used a fuse in this line.