Yes that is true, I have never known anyone that was called out on this. However I am sure if an invention becomes popular and really valuable that some organisations, espcially big ones, would not hesitate to give it a try.
I had a discussion and got a clarification on the scope and we agreed that it covered specified things with work applicability, so I'm satisfied now (will start work on the best selling novel and string of number one hits right away!).
It was important it wasn't just based on a vague ill-defined idea of "outside work" because typically a portion of what is clearly work related IP I generate doesn't happen in a formal work situation, yet I understand it as work (and am fine with that) whilst equally there is plenty of non-work IP that is just as clearly in no way work (as it doesn't relate to our line of business).