How does that prevent AI from becoming superhuman in all intellectual domains, thus creating ASI? We set "become good as chess" as the metric and it became superhuman in that domain.
> The problem is what happens when you max that out.
I'm not sure how you conceptualize "maxing out" the intelligence metric. Again, taking chess ability as a proxy metric for intelligence, there is no reason to believe we have maxed out chess performance, but AI is already far superior to humans. And better bots are created all the time. There is no need to design a new metric to improve chess performance. The old "How many currently existing players can I beat?" is good enough. Also, why couldn't it design better metrics after achieving superhuman intelligence?
But even if we suppose there is some kind of fixed point limit to this process, it would still be far above human level. That is all that is required for ASI.
Regarding X-risk: the point is that it becomes easy even for people who, unlike you, haven't studied biology. For things such as atomic war, the AI does not necessarily need to acquire the materials. It can access them digitally by hacking the weapons systems, possibly in collaboration with some human actors. Or maybe it spoofs detection systems causing countries to fire upon each other. Generally, it seems to me that the barrier to entry for bad actors to cause these scenarios is decreasing. Whether these scenarios are more likely than D-risk I don't know.