While Blue on Blue is naturally an occupational hazard of warfare, like any occupational hazard this does not mean it should therefore be accepted as inevitable. That is not missing the point but taking the real world as it is and trying to reduce the likelihood.
That said, the covering up of the facts of this case (or any) is indefensible and now that the facts are public knowledge this case must now be properly and fully investigated and any culpable persons brought properly to book.