Indeed, as the authors of the article write:

> While Grimm believed that many folktales were likely to be thousands of years old, only a tiny minority can be traced back to before the emergence of the literary fairy tale in the sixteenth and seventeenth centuries.

The "reconstructions" of the authors are based on fantasy. They try to sidestep the massive problem of possible literary origins by manufacturing data with their magical phylogenetic device. It's garbage in, garbage out.

he meant that any evidence we have puts a ... "floor" on how old something is, but it doesn't rule out it being even older. He wasn't using "we think" to mean "we imagine", he was using it to mean "we believe from evidence"