There is a difference between nudity and sexual nudity. If he saw his mom stepping out of the shower, no big deal. If he saw her performing for a sexy video or something, that is another story.

I live in a province where top nudity is legal in public for woman. I think at least the chest is not bad in anyway for a child to see.

But it also comes to comfort. I read on here a story about how boys in some school were made to shower naked after gym class. So although non sexual nudity is no big deal for me, making it expected (like in the case of the showers) is not ok.

There is a lot of nuance to these kind of things.