Exactly right, scrummasters should be outside of the business and developer chain so they can uphold the process first and foremost. One of the phrases I hate the most is "we're in crunch time, we don't have time for process." No, that's when you need process the most! It doesn't matter if it's crunch time or whatever, PMs and business sometimes needs a reality check on what is possible and what isn't, and developers need someone in their corner that isn't also their manager.