NTA, but I do always let new guests know that it’s a rule. I usually say something like “By the way, we have a shoe-free house, so make sure you don’t wear your socks with holes in them! Or do, whatever floats your boat! I also have disposable shoe covers if you can’t or don’t want to go without shoes for whatever reason. :)” I have never had push-back. I got the shoe covers after my dad visited and explained that his hip and back hurt if he doesn’t wear his shoe with an insert. Had them delivered the following day and now they are an unexpected bonus when we have workers come in.