I never felt the need to be polite to strangers when they attempted to touch my DD as a newborn. My kid, my rules. The second I saw them reaching for her, I would immediately block them to prevent them from touching her (or, if she was in her Moby wrap I would turn to the side so she was out of reach). In my experience, most people are understanding and won't try to touch a newborn. Those who didn't seem to "get it" got the stink eye from this mama and a firm "do not touch her, please and thank you", LOL.
"Don't tell GOD about your great big PROBLEMS.
Tell your PROBLEMS about your great big GOD."