As I'm not familiar with the work you're questioning I won't be answering in relation to it, but I did want to address the idea of revisionist history being something inherently less reliable or legitimate than non-revisionist history.

All historical revisionism is is the challenging of the orthdoxical narrative of the past through the examination of the past through a different light. Though its led to problematic occurances such as holocaust denial, it has also led to most positive occurances as gender and cultural history.

A book being revisionist or even counter-revisionist (the challenging of new orthodoxy as a result of past revisionism) doesn't make it less reliable or legitimate as a historical source nor should it be a criticism of the work - what one should be looking at is the overall argument of the work in relation to its source use, the coherence of its argument, and its historiographical methodology, among other things.

In short, whether or not this work is revisionist should play no bearing on its legitimacy or reliability as a historical source.