I read the GJ indictment basically the same way you did, but that only led me to believe that it was Burke instead of Patsy. I still am not 100% convinced though that it was not just a sort of "best we can do" indictment since they were unsure of which of the 3 Ramseys did exactly what.
However the idea that the Ramseys covered up for someone outside of the family is, IMO, the most absurd of all. I could accept the IDI theory over that. There is no way they would cover up for a non family member. That is patently absurd, IMO.
I know the next step for some is finger pointing at JAR, but I don't buy that either. First there is not a shred of evidence that he was in Boulder. Second, I am a stepmother of an adult stepson and he has been part of my life since he was five. I truly love him. That said, there is no way on God's green earth that I would cover for him if he murdered my child. Or anyone else for that matter. John might have protected him, but I don't believe that Patsy would have.
The only person John and Patsy would realistically cover for would be Burke.
This is what I believe as well. I did not mean to suggest that the parents were covering for someone else outside the family. I read the GJ indictments as inferring they covered for BR. And BR could not be named in any indictments because of his age. That is why the GJ and Kolar have to "dance around" the blame. The finger can be pointed at BR, but it can't really "touch" him.