This sounds like a funny "blooper" story, but could just as well be an entirely normal history of the solution to an important problem. Many important theorems are proved by contradiction, and for all we know, the question of the existence of partially uniform k-quandles could have been a difficult unsolved problem.
There is a similar story -- whether true or not I don't know -- told at Oxford about Cambridge and at Cambridge about Oxford. Someone wrote a thesis on anti-metric spaces, which are like metric spaces, except that the triangle inequality is the other way round. He proved all sorts of interesting facts about them, but at the viva, the external examiner pointed out that there are only two anti-metric spaces: the empty set and the one-point set.
It is recounted that the student passed, but his supervisor was criticised for not having picked up on this earlier.
A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).