Why is there low hepcidin levels in hemochromatosis?
From what I remember it all depends on which type of hemochromatosis we are talking about. There are several types depending on the cause and some of those like the hemojuvelin gene mutation-related have low levels of hepcidin as the CAUSE of the hemochromatosis (since like you mentioned, seeing it as a consequence wouldn't make much sense)
The first 4 pages of this paper should clear things up a little bit https://www.aasld.org/sites/default/files/guideline_documents/Hemochromatosis2011.pdf