If human brains can do it then it can be done. And it can probably be done better too. I don't see any reason to assume our brains are the most energy efficient computer that can be created.

Also, my original argument is not about wether AGI can be created or not but wether we could keep it in a box.

Anyway, it's just a philosophical thought experiement and I'll rather discuss it with someone that's a bit less of an dick.