Well, I'm still not convinced that "no answer" is the intended response. "No footed" makes as much or more sense to me and sounds more like an actual answer.
But by definition, the possible answers in a crossword puzzle are supposed to be limited by at least one letter having to also fit with an intersecting word.
Unless we can fill in at least one letter by way of an intersecting word, and without a factually correct answer (as with, say, an author's name or a geographic location), unless the puzzle maker tells us what he/she had in mind, there really is no clear answer. (That means that even "no answer" can't be definitively shown to be the intended answer.)

Without an intersecting word/clue, that thing about what's worse for a polar bear than being a southpaw isn't really a crossword puzzle clue. It's just a riddle of sorts.