I guarantee you there’s no job at Google that solely consists of trying to find new language to ban. That’s absurd.
1) A team is tasked with providing suggestions to improve emails
2) "Inclusive language" or avoiding potentially insulting language is added as a feature by higher ups
3) The more entries in the "Inclusive language" feature the better the outcome looks to management or it helps meet some arbitrary employee metric (velocity or x issues resolved or similar)
4) More and more entries get added because it is easy to do