I really do not understand why the "core team" has a 2X problem.
Without 2X is not Segwit. Bitcoin has exponential support, so 2X is a good compromise.

... ok I understand that they want to create a "market fee" and "birth of side chains" as soon as possible.

The war between Bitcoin and Segwit2x will damage both sides and finally 2X is necessary (only the of time question)