A "chain split" is not possible here. You can only have a dead soft fork or BIP 110 conpliance. Also, this is literally always possible by miners but nodes keep them from changing the rules (by validating their work.)

That's not how that works. If no one cares about BIP 110, it just dies. There's no chain split.

There is a religious fever going on in 110 land, try talk to them. They are angry, big feelings.