The problem emerged with this answer (deleted, and so invisible for users with less than 10k reputation)
The most relevant win criteria of the puzzle is the algorithmic complexity of the solution.
An answer using Mathematica was posted, making the algorithmic complexity of the solution depending heavily on the internal algorithms used by this software. These are not enough well known, and practically unknowable, because Mathematica is closed-source software.
However, the solution seemed a quite interesting one for me, and maybe also for others (it got multiple upvotes).
Accepting the situation, the poster declared the solution as non-competing.
Despite that, it was deleted by community votes.
I think, also non-competing or undecidable answers improve the site. However, it would be probably not useful to have a large mass of non-competing, unanswerable answers. Furthermore, the primary goal of the site may be to collect mainly competing answers to the puzzles.