We have made an adjustment to DU's "No bigotry/insensitivity" rule: please read

[Ms. Toad]

244. You are elevating "rules" over people.

Never a good look, especially when you are actually ignoring the rules.

Jerry wrapped their hands around the coffee cup.

They are coming over for dinner.

You use the form of the verb which matches the pronoun. They is a plural pronoun, so you use the plural verb form (even when you are using they to refer to a single person).

Someone who is serious about it being a grammar issue, rather than a reluctance to use the person's pronoun, would listen to how people who honor personal pronouns speak or do a little research. It isn't hard to find using Google, or any other search engine.

Here's a link to the American psychological association's style manual on the matter. https://apastyle.apa.org/style-grammar-guidelines/grammar/singular-they