I think the root of the issue I am getting backlash on is team work vs individual work. If you are using Agile as a process to just organize work then ignore all my comments. I am using Agile/Scrum as a way to build strong development teams (not just groups of individual developers).

For the locking sprints, that is a matter of protecting the developers from management and the customer. The product backlog can be moving target all day, but the sprint backlog needs to have some backbone so the developers have focus and are not pulled different directions every day. If the sprint backlog needs to change then the developers will come to me for help. Our history is from a very chaotic environment and the developers really like having some sanity/consistency with defining the sprint and holding it still. If the customer wants something else, then we can deal with that in the next sprint.