"One option could be a (for sure costly and needed to build)...

"One option could be a (for sure costly and needed to build) pre-benification and directly cut off the thorium & uranium content in Australia"

Not as easy as you suggest. In the late 1940s there was considerable effort made to extract the thorium from the monazite content in beach mineral sands. I was involved with this as a trainee industrial chemist. The process at the time was conducted in a pilot plant set up to extract the cerium and that plant was a similar process to the current one used by Lynas. I spent three years associated with this project. To extract the Thorium would mean conducting all the processing in Australia. You have heard of the Australian Greens?. Those in Malaysia are novices to the ones we have here.

Maybe the alternative is to extract the thorium as another product but I'm not sure the locals would settle for something like that. Pity because thorium could replace a lot of uranium and pose less problems. The thorium content at Mt Weld is low so the yield may not be economic anyway. Because the level is so low it does mean that it should be able to be disposed of in road base or in fertiliser. I suggest that the plans Lynas has in this regard is by far the best and safest method of disposal.