The second example does lack braces in two nested 'if' statements. Did you ignore that? Granted it is not three levels deep and granted there is a brace in the 'else' part but that's no reason to ignore the fact that K&R does in fact omit the braces for nested 'if-else' statements.

Demanding now that the nesting has to be less than three levels deep to omit braces is just moving the goalposts.