>Is your belief then that ASI is going to be producing computronium or something, then?

That's one plausible course of action, although being only human, I can't say with any certainly that it's the correct one.

>And what's the need for this apparent hyper optimization task the ASI is going to embark on?

Somebody's going to tell it to do so. E.g. "Find as many busy beaver Turing machines as possible." Only needs one person to make this mistake for everybody to die.