I posted the study because
1) OP is a casual cyclist who wanted to lose weight (not a 25 mph time trialist)
2) several posters have responded that a low carb diet is unhealthy, blah blah blah, one even blamed his unfortunate heart disease on meat/cholestoral issues. I just wanted to point out that these views are based more on dogma than actual science. the actual science is steadily disproving these notions.
now, as to whether nor not someone can do your TT at 25 mph on a low carb diet, you could be right, I honesly dont know. at that level, perhaps you do need carbs. but that is irrelevant to OP's concerns. Regarding the 400 miles per week on a low carb diet, that is certainly doable, and I would argue easier to do for an athlete who has adapted to a high fat/low carb diet, as you do not bonk, you do not have the lactic acid issues, etc. etc.