BBM. I don't believe you are quite correct. Because of his age, Burke could not be prosecuted but he certainly could be named as a suspect yet LE have refused to include him as being under the same "cloud of suspicion" as his parents. Once the Ramseys were made aware of the fact that Burke could not be charged because of his age, there was no reason to continue with their deception and charade yet they did. It isn't a giant leap to conclude they were covering for each other, not because Burke did anything.
The GJ did NOT indict the Ramseys because of the actions of Burke, they were indicted because of their own behavior.
I do not believe he could have been publicly identified as a suspect. So we'll have to disagree on this. Yes, the parents were indicted on their own behavior, but there is no reason to assume they were only covering for each other. The main thing is- covering for their son can't be ruled out. Even if the parents knew he couldn't be charged, I feel they would not have wanted him to be attached to this crime in any way. Getting him "help" was not on their radar. They wanted this to stay as far away from him as possible. A complete and total blackout as far as BR was concerned.