I agree he probably already knows he doesn't have to say anything, but I've been surprised how many people will still talk to me, especially when they're lying on a stretcher with severe injuries.
If they do administer Miranda, and he agrees to talk, they can't question him at all and get anything useful, because of his condition.
At least under the public safety exception, there is a chance at discovering new evidence. I think you bring up important arguments, and I don't think you are wrong. A liberal judge may indeed throw it all out. None of it would ever even make it into the courtroom if they Mirandize him, though.
Did the officers act “reasonably”? Did they act in “good faith”? What if the Obama judge is convinced the officers MUST have heard the kid say clearly that there was no danger in relation to the locker, and the judge concludes the cops acted in bad faith by proceeding further themselves.
EACH of the elements of the exception is ammunition for the defense.
Experience teaches that unless one has very strong reasons for doing so, one doesn’t play these things close to the line. There is too much opportunity for things to get unstuck down the line.