The community was already split over SegWit as a scaling solution compared to an on-chain block size increment, well, that and SegWit itself as a soft fork upgrade to the bitcoin client. The proof of an existing split in the community pre NYA lies in the crystallised UAHF and to a minor extent the doomed UASF. That is irrefutable, therefore the ludicrous claim that the NYA caused the split is laughable to say the least.
But you again purposefully miss the point of the mailing list. The terms of reference of the NYA WG were not to split the network and the list was established to aid in communications while developing the client under those terms. It should go without mention that any opinions (even code) expressed on the list that is contra to those terms of reference can not be binding, let alone persuasive.
Whether persons like myself view the btc1 client as the long awaited opportunity to “fire core” (and express the same on the list) does neither alters the NYA WG ToR nor makes it wrong. Brilliant as they supposedly are, they are toxic, have chased so many good devs from bitcoin development and have hoodwinked you and your ilk to believe they are the indispensable. To hell with the lot!