AFAICS, the proposal is to build a single entity, that never dies, and faces no competition - and so is not subject to natural selection - and is engineered in order to preserve its aims.

We haven't seen such entities before. Animals act to preserve their aims (gene propagation) - but are pretty primitive, and can get flummoxed in unfamiliar environments. Religions, companies and organisations are typically larger and smarter - but they compete, face natural selection, and are moulded by it. Consequently their aims tend to converge on whatever results in their inheritance persisting.