I've been reading about the Native American language isolate Washo, and looking at the Universals Archive. If an ergative language is SOV, the object and subject affixes will be prefixes and the main or only alternative order will be OSV. But why is the prefix order osV rather than soV? If the subject and object prefixes are reductions of independent pronouns (and in Washo, they seem to be), one would anticipate soV from SOV.
You make a number of assertions that appear to be unfounded/misguided:
So what you've asserted about the language is that:
From this, I would draw the conclusions: