Dude, he didn't win the tour...
and in track and field marathon runners never win the 100 metres either, doesn't make them less significant athletes. One of the beautiful aspects of a grand tour is that the different categories are all wrapped up within the one race.
A stage win in the tour can be enough to make a cyclists career, consistently winning a handful is exceptional, he and his team make it look easy at times but if it were that easy other people would have done it over the years.
As for SPOTY It does make you think that maybe they should have a separate category for athlete of the year so that proper sports don't have to mix with the ones that don't require the participants to be fit.