Heh, trusty Feynman! I'm an expat and I can't tell you how many times people have pounced on me for using a regional expression that they understood perfectly well. "In this
country we don't say that", as if it's illegal to use a different saying.
Gender-neutral pronouns are a tricky one. There are a couple of interesting proposals, including "s/he" or "ze". Extending the use of "they" is probably the most viable, although it does lack a bit of grace. I don't know if you're male or female (or something else), but I'm male and I get a unique thrill of alienation when I hear someone say, "Anyone should be able to eat ice-cream for dessert if she wants." I love it! I'm happy for speakers to use "he" or "she" as example people, so long as both are used in roughly equal measure.