I think this is a coincidence as well.
By the way, a similar coincidence occurs in some Sino-Tibetan languages where the word/prefix for ‘not’ is the same as the word or suffix for ‘mother/woman/female/older.sister’. In Burmese (which Okrand has studied at least a bit), both affixe are written မ. The pronunciation is slightly different: for the negation prefix it is /mə-/ and for the female suffix it's /-má̰/.
I'm not saying that Okrand's study of Sino-Tibetan languages have influenced Klingon here. It might really just be a coincidence.
Best,
— André aka Vortarulo