Having the largest Pt producer as a major shareholder may not necessarily be a good thing in the long term.
More suppliers of Pt means lower prices .
Anglo's strategy may be just to put its foot on the project to keep market share for its south african mines.
I'm not saying this is true just a possible scenario.
Look what happened when Xstrata bought into the Windimurra vanadium mine then closed it down to keep the world price high.