Miranda is not required to ask this guy a number of questions about imminent dangers to the public.
Not mirandizing this kid as a practical matter gains nothing for the reasons I gave, but potentially could seriously complicate the prosecution.
If the defense lawyers can successfully challenge the exemption, then not only the statements made by the defendant must be excluded from evidence, but also any OTHER evidence that in turn is found based on clues from the inadmissible statement (the fruit of the poisonous tree doctrine). There are a number of exceptions to this exception, but you've just handed the defense something to fight with as you litigate whether it falls within the exceptions to the exception. You get a stupid judge or a left-wing wacko judge, and the prosecutors might get screwed.
Since Obama is not going to enhance interrogate this guy anyway, just read him his rights and get on with it.
You are assuming that imminent dangers to the public exist. I doubt that. The gunfight is over, now comes the legal slog to see to it that the man never sees the outside of a 10z10 concrete box in Colorado until the day of his execution.