Since the hashrate will be extremely low, what is going to prevent a hash attack? I do not understand....

Fork?

You're confusing two camps.

They will finally have a pure chain that is blessed by Lord Luke. Nothing else matters.

Glory

Implement some feature that core was blocking (ctv?), prove their superiority, watch everyone buy their coin, profit. At least that's the closest thing to a plausible narrative I've seen. Add "milk the suckers that believe it dry" for the more cynical participants.

Maybe nothing. They’ll mine silently while no one cares and when the consortium implements tail emission in core coin 110 coin will up only and everyone will want the real bitcoin but will be kinda too late.