Why did DOJ silence the singing canary?

<p dir=ltr>In a Boston hospital, the Boston Bomber was talking freely to the FBI, that is until a team from DOJ walked in, complete with judge and defense attorneys and read him his Miranda rights. This shows how dysfunctional this administration is, since Holder as AG oversees the FBI, yet word is that the agents at the hospital were not happy about losing the useful source of terrorist information.&#160; What would of been the impact of waiting before airing down the stream of information?&nbsp; Worst case, everything that the bomber said could not be used in evidence against him. However, there is the Public Safety clause that might allow for some of what he said to be used. But more importantly, was anything that he said really needed in his prosecution? We have video and photos, the statements of witnesses at the scenery of the bombing and what was said to the victim of the car jacking.
So the question surfaces, why did DOJ decide to afford the suspect the right to silence and an attorney to advise him to shut up?  Is there something that they do not want to be aired on public.  This "most transparent" administration has a record of telling the most and the most outrageous lies, is this just another example of their devious ways?
Unfortunately, we may never know all the answers as King Barry is the best White House resident ever at suppressing and blocking access to information related to him and his court