Anyone who really knows cycling knows enough about the TDF to say, without a doubt, that these time trials cannot be compared to the in-race TDF splits. L'Alpe has never been the prologue, which is the only time the TDF racers mount the bike with fresh legs. For validation, have those same Kenyans ride every stage of the tour up to that 2004 TT and then see how fast they can ride.
Hell, you can even dope them if that is what you believe all TDF riders do. The result will be the same - poor. Those runners do not have anywhere near the muscle mass to arrive at the bottom of that stage, let alone make it to the top in stellar times. Do you want more validation? Check out how the local stud runner fared when they "jumped into" a triathlon or duathlon without some serious bike miles behind them. It has happend where I live and they have always had their ass handed to them when even descent cycling talent was there.