You might want to work on your grammar, my friend.
'Tis meet that some more audience than a mother, since nature makes them partial, should o'erhear the speech."— Shakespeare, Hamlet (1599);
Caesar: "No, Cleopatra. No man goes to battle to be killed." Cleopatra: "But they do get killed" —Shaw, Caesar and Cleopatra (1901);
In an 1881 letter, Emily Dickinson wrote "Almost anyone under the circumstances would have doubted if [the letter] were theirs, or indeed if they were themself."
George Eliot (1859) – Adam Bede: “It is too late to spare anyone when they are dead.”
So you would say that when referencing a singular specific person of undeterminate gender in the third person we should use is? Because I am quite sure that, if that has ever been correct at all, it certainly isn't now. As per merriam webster: A student was found with a knife and a BB gun in their backpack Monday, district spokeswoman Renee Murphy confirmed. The student, whose name has not been released, will be disciplined according to district policies, Murphy said. They also face charges from outside law enforcement, she said.— Olivia Krauth
E: also, "Each member [of the women's touch football team] found something they could improve on in the future."
Dalby (Queensland) Herald (Nexis) 21 October 16, 2014 (as quoted in the oxford english dictionary)
Contradicts you as well unless you'd like to argue that "each man are fighting for himself" is correct.