The spec may say one thing in this context, but that is only guidance. Technically, the response header says nothing about the body: they are entirely separate

The spec may say one thing in this context, but that is only guidance. Technically, the response header says nothing about the body: they are entirely separate things. You can have any response code, and a body may or may not be present, regardless of the spec. So yes, it is correct to say that response codes say nothing about the body.