I seem to recall reading that one canoe went to a local scout group (or similar) while the other was kept by the builder after all!
Perhaps disposable is the wrong word to describe these. Probably better to see them as quick and cheap to build, fun to use and because of their relative "cheapness" (in terms of the time put in and materials) it is easy to give away to someone who can put the canoe to use after you are done.