As I understand, they are hoping to achieve fusion ignition, where no additional external energy will be required to generate power. So current efficiency calculations are irrelevant in that case.
they also say this isn't possible with their current techniques.
That's fine by me, it was not very long ago that we were unable to get more out of the fuel than we put into the fuel. That's step one to fusion ignition, and was done for the very first time last fall, so as far as I'm concerned they are still fleshing out step one.
