Re: Thor 2 Dark World news, speculation and pictures possible Spoilers - Part 5
Personally I can see Balder being hid away because he might have more knowledge on how to use something like a Tesseract, and to be safe from others trying to force him into doing things, they hid him away.
Responsibility, Duty, Honor these are not
mere virtues to which we must aspire
they're Essential...to every soldier
....to every King.
Coulson, "If the details of this gets out, the operation would be complimized"