Id be more inclined to think the MD role in a new Lithium...

Id be more inclined to think the MD role in a new Lithium company with serious potential was his opportunity to make his mark in the mining industry.
He has developed his skills with RIO and climbed as high as he wanted/needed to before grabbing this opportunity.
This is a chanc to Better his future credentials, provide a greater professional challenge and be part of a new upcoming company changing the way we live.

Is CXO big enough for RIO?
CXO has resource but its not that big... potential for more but why jump in with all that work still to do to be proven.

I wont put anything off the table as it reminds me of the RIO take over of Riversdale mining in 2010. It came out of the blue and they paid 3.6 billion for 10 billion tons of coal in Mozambique. Talk about a switch of focus