Just speculating here, but the only reason for going through all this trouble would be:

1) friendly separation from our Chinese friends. They get C-O and Evans gets T.P and/or

2) pocketing a government support cheap money, probably north of 500mil in order to build T-P without a partner, assuming that there is a requirement somewhere, that the entity must be US Entity (but here, I am not sure, why could not Lithium America apply?)

3) C-O is potentially in troubles due to pollical environment and they don’t want to be part of it.

The "unlocking value" argument sounds fishy. Is Evans suggesting, that without the separation, the revenue/profit would be somewhat less? If no, then unlocking value for whom? It is clear, they are just testing the reaction to this idea at the moment. But I guess, without an insider info, it is hard to determine, what they are up to. Unless of course someone here has already made such "unlocking value" and knows what is going on. I bet, WB sees into into that bit more, than he is sharing with us :-)