Burke was never a suspect. If you read early analysis of this case, no one believed he was responsible. Kolar and the CBS show pointed to him many years later. No one leaning BDI would clear him anyway. They could see nothing at all or some behavioral concerns or any other records and people would justify he still may have done it.
It accomplishes nothing, would not clear him no matter what it shows, and opens him up to intense scrutiny as a 9-year-old child. As a parent, I would never open my child up to any public scrutiny and my children have absolutely nothing of note in their school records, either. One line by a teacher: “Burke can be a bit impulsive when completing his multiplication tables,” would be picked apart on forums like these as evidence of murder.
Jmo