You know you are in for a good time when you get to the chapter called "Sexual connotations".
I'm not an expert on the field, so I've read the paper, but am not qualified to draw conclusions from it. But as I read it, the focus is more on the role of ritual and religion in the making of the iron. And the transfer of knowledge through this process and hypothesize the addition of the burning of bone is actually beneficial.
However they do not approach this from a material technology standpoint. So I would love for someone with knowledge on this point to chime in. It's very interesting if the people back in the day knew how to make low carbon iron and the little bit of carbon they did add came from the burning of the bones. But as I see it the burning of the bones is more a ritual kind of thing and getting all of the carbon out of the iron is the harder thing to do, not putting the carbon in.
I remember when I bought an 40MB hard drive back in the day. (Yes, megabyte, not gigabyte) And I labeled it "WOWSOBIG", because it was huge for me. When I bought a 32" flat screen when those first released I thought that was big. Now even the TV in the bedroom is a 48" and that just the small secondary TV. One of my neighbors across the street has a TV as big as his wall, I can watch his TV from my window.
Funny how perspectives change over time.