I have seen those census and wondered the same thing. I had put "free-trader" on that query by mistake. It was to be "fur-trader". There are supposed to be fur trader records showing Seth Austin with his Souix wife selling furs. I think the records were supposed to be in some books in Colorado.
My gr.grandfather was born in Hart County KY-- Thomas Austin, 1893- I noticed you are from KY. does that ring a bell?