You're misunderstanding the issue. Core / Bitcoin.org don't have a problem with Segwit2X which is a UASF like Bip-148 which core supports. (It uses a different BIP and is slightly different but it's perfectly find with all of us.)
The threat is that BitMain, the controller of a very large amount of hashing power, something like %70 is threatening a hard fork into their own, non-segwit chain:
Sorry, that's completely wrong. "UAHF" is even less likely to happen and gain adoption than UASF. BitMain does not directly control all of the hash power of people using their miners and cannot successfully fork by themselves, plus again they would have no support from exchanges.
Core absolutely does not support Segwit2x, because of the hard fork later. If they do, why don't they merge it and end this standoff?
The threat is that BitMain, the controller of a very large amount of hashing power, something like %70 is threatening a hard fork into their own, non-segwit chain:
https://blog.bitmain.com/en/uahf-contingency-plan-uasf-bip14...