First off Lance is a freak
Second Lance does TONS of intervals all road racers do. It's the tri geeks, some XC mountainbike racers, and tons of "fitness enthusiasts" that try to get away with LSD only.
Third the big sprinters are only faster when the going is flat this is true for any sport. If sprints were raced uphill you'd find a lot of skinny guys with huge legs winning the races. Gravity is the confounding factor, or in the case of rowing water displacement.
I think the power ratio that the concept people use is flawed though because it asumes that drag on the hull of the boat has a 1:1 relationship to water displacement. If this was true heavyweight crews would be slower than the light weight crews, or there would be no real difference because the light weight crews would make up for the lack of power with greater eficiency.
I dont think Lance would actualy row faster than a big elite rower but he does have a higher power to weight ratio.
Funny I was just thinking that female gymnasts probably have some of the best power to weight ratios going for short bursts