The DFS is required in order to get financing, don't know why...

The DFS is required in order to get financing, don't know why you think it is pointless. Do you think that they are just going to go and start constructing a mine without determining the "feasability" or economics of it?
SIR is aiming to have a low debt/cash ratio financing deal so they don't require to hedge. See https://au.news.yahoo.com/thewest/news/a/24546464/cash-in-bag-sirius-heads-to-the-bank/ might help you understand