Half-life means the time until only half of the atoms are left, but we don't have to wait that long to measure the speed of decay. Just like we can measure the speed of a car, without waiting for it to reach the finish line first.
Unironically, I'm willing to accept that as head canon. Scull deformations were done by many cultures all around the world. For Emps they might be classical look, that he tried to bring back. And the other perpetuals said: "don't try to bring cone heads back, they're so 1000 BCE"