The concrete danger of taking brains without consent is that it upsets the family of the deceased, and the rights of bodily autonomy and respect for the deceased outweigh the rights of an unrelated person to have a specific body part in their collection.

A second danger in this particular case is that a brain may be used as evidence for a political program to restrict the rights of some population. It is totally legitimate to deny access to your body or your family's body if you don't want it to be used for this purpose. Scientists are human beings and not objective, and just calling something "research" does not magically make it objective. In this case, the research program was a political tool of no scientific value.

I'm sorry for my short reply before, I thought the article made both of these points very clear.