The reviewer writes "That some questions about inequality are obscure or ill-framed does not indicate that inequality of wealth is not a fundamental social problem."
Graeber's point about inequality is that, as a rights concept, it's impossible to define, and also not a good representation of how good communities work.
The reviewer is bending Graeber's words to suit his own points (and publications!). "Inequality of wealth" is a redundant misconception for Graeber, since wealth == inequality.