Well, without actually reading the article itself I'll venture an opinion of course. If you carried the fuel and lasers yourself it wouldn't be like the sailor blowing on his own sail at all; it's be like the sailor facing the stern and blowing his ship forward. That's because the ship would still be powered by the rearward expulsion of electrons.
The advantage of the system with an external laser is (I presume) that even though it is no doubt very energy inefficient, since all you're expelling is electrons the specific impulse would be quite high. This allows you to apply small amount of thrust, but continuously for a long time without the bulk of your payload being fuel. If you are going to carry the fuel needed to power the thrusters you might as well go with compact ion thrusters.