From Witztum's explanation so far we can infer that he is going to use the definite article, as otherwise he wouldn't have brought it up. That gives him four possibilities to choose from. He can't really do that here, because he knows that the spelling rules given in all three of his papers that are mentioned above select the short spellings. He wants the long spelling, so he has to do something else. Oh dear, a Halachic source used as a spelling authority.
Most people use a dictionary.
Of course, he is not really using the Mishna Brurah for the spelling. The edition of Mishna Brurah printed with nikud uses the short spelling XNKH, but this time he has to suppress his usual preference for vowel-reduced spelling and hope that nobody notices. In any case, he is not interested in correctness here. So he looks around for a place with a few good words that appear in the same sentence. There are thousands of sentences to choose from, so perseverance is the only requirement.