jinjuku
This person" is singular so the correct word is his. Singular possessive. Case closed.
"Their, them, themselves, they (as singular pronouns)
Many English speakers believe that using the plural pronouns they, them, themselves, and their in gender-neutral singular constructions is incorrect. For example, these people would consider the them in “call a friend and ask them to come over” to be wrong because them by definition refers to multiple people, whereas in this clause its antecedent (a friend) is singular.
But there are problems with this view."
You are inferring a gender when it hasn’t been provided to you. Keep on swinging and missing.
>>>>Again with the logical fallacies. English must be your second language. Not that there's anything wrong with that. Except when it comes to English grammar.
"Knowledge is defined as everything that’s left after you subtract out all the stuff you forgot from school." - old audiophile axiom