NChain mining

Just trying to understand a few things....

...in a recent video (Tokyo presentation July 20th), Craig Wright mentioned that NChain would mine and follow the longest chain. As BCH has split from BTC and became a shorter chain, does that mean that NChain will never ever mine the BCH chain or consider it to be the true "Bitcoin"? The tactic to reject (by ignoring) segwit transactions would seem to support this, i.e. NChain will mine the BTC chain (longest) and will endeavour to keep it segwit free when it activates. NChain will verify blocks with segwit transactions but ignore segwit transactions for relaying and putting into their own blocks. If they get decent hash power then it would slow down segwit miners and disadvantage them... a very clever tactic to keep segwit out. He went on to mention that NChain's software would increase the block size limit. Wont this cause a chain split? How would NChain ensure that their bigger blocks chain is the longest? Just trying to get my head around it all.