

Why should it be the case that settler-colonial projects can only be compared to other settler-colonial projects? Fascism is fascism whether it’s in support of settler-colonialism or imperial expansionism. Yes, it’s a valid distinction to make, but it does not invalidate comparisons to Nazism.
What you’re doing is a bit like seeing someone compare bees and ants on the basis that they are both colony builders and saying the comparison is inadequate because bees do it to make honey and ants don’t.
See my comment below.