The verdict is in: the beer bike is too wide to be on the road as a bike and cannot be wider than 1,50 metres. A recent accident in Amsterdam involved a beer bike that was 2,20 metres wide and made it more of a vehicle than a bike, which is illegal.
People do have to peddle it to move it forward:
(Link: blikopnieuws.nl, Photo of Beer bike by Taco Witte, some rights reserved)