That's by design, for maximum disruption. A hostile takeover attempt by any reasonable standards.

I think splitting BTC-B2X will require mixing freshly mined coins into one's transactions. The landing chain of the transaction will be the chain where the fresh coins were mined. I still have to figure out how to do that.

There seems to be a different way invoving timelocked transactions - but I won't have a clue about this bit of magic until I research the matter. BTW, for the technically knowledgeable: pointers would be welcome