I interpret this as the “boundary” being one-way away from us, with us at the “top of the potential well”. As opposed to the more commonly proposed idea that the universe is inside a black hole.

Hawking radiation is based on the curvature of the event horizon, so in this case I think it should balance negatively, sucking out energy from the universe, probably by releasing negative energy particles in the particle perspective.

This doesn’t make physical sense, which matches that such an event horizon shape also doesn’t make sense and shouldn’t be able to be created I think.