This discussion reminds me of a story of a Rebbe visiting a rich guy’s house on Shabbos. When his little kid touched something that was muktzah the father wouldn’t admonish him because he’s too young to understand. Then the kid touched some expensive breakable Tchotcke and the father started screaming at him to stop…
I don’t remember all the details of the story, and I’d assume the kid was older than an infant, but I believe parents have the ability to set rules and enforce them WHEN THEY CONSIDER SOMETHING IMPORTANT. I haven’t read the book so I can’t comment on it, but the bottom line is we all need to find that “happy medium”.