This means that he is cruising at a manageable effort, at a speed which causes other riders to dig into their reserves to keep up, and building up fatigue poisons (lactic acid) in their muscles.
Look at the hurt he put into Jan Ullrich at Alpe d'Huez last Tour, even though Jan was arguably the biggest real threat in that Tour after Lance.
But nothing is for certain, Lance depends on his teammates for protection until the climbs, for shuttling food/water, as bodyguards to keep him away from crashes. No one can win the Tour alone.
I would agree, to a certain point, that no rider can do it alone. However, I believe last year during a climb, a breakaway killed Lance's team, and he had to do it alone...and he did. Of course, this would be why he is the featured rider on the team.