[pangram]

They assume an upper limit with 100% efficient conversion of matter to energy, so changing the energy production method shouldn't make a material difference. EDIT/UPDATE: Realized you might be talking about the total energy budget (i.e., their total energy budget that is then multiplied by the "Space Devotion Ratio.") Yeah, that could advance the timetable by some amount.

[Ralith]

Additionally, the only mention I see of matter to energy conversion is an aside about efficiency of propulsion technology, not energy generation; it doesn't appear that they evaluate matter-energy conversion as an actual energy source at all.