It was intentional, yes. Tread is they/them nonbinary (like myself!) but I think what the original comment was referring to was the wants/knows aspect. In that case it was also intentional as Kabir is meant to be from a Russian background and sometimes slips into a more Russian dialect and uses English incorrectly when he's frustrated or angry.
I was speaking about the inclusion of the s at the end as well, but turns out for an entirely different reason lmao.
I just figured that because the sentence would be written that way if either "He" or "She" were used as the pronoun, you changed it out for "They" but kept the rest of it the same. Didn't even process that it was an (intentionally designed) mistake on Kabir's part