The way to fix the quoted argument is to have the utility function be random, grafted on to some otherwise-functioning AI.

Not demonstrably doable, arises from wrong intuitions arising from thinking too much about the AIs with oracular powers of prediction which straightforwardly maximize the utility, rather than of realistic cases - on limited hardware - which have limited foresight and employ instrumental strategies and goals which have to be derived from the utility function (and which can alter the utility function unless it is protected. The fact that utility modification is against the utility itself is insufficient when employing strategies and limited foresight).

Furthermore, an utility function can be self destructive.

A random utility function is maximized by a random state of the universe.

False. A random code for a function crashes (or never terminates). Of the codes that do not crash, simplest codes massively predominate. Demonstrably false if you try to generate random utility functions by generating random C code, which evaluate the utility of some test environment.

The problem I have with those arguments is that a: many things are plain false, and b: you try to 'fix' stuff by bolting in more and more conjunctions ('you can graft random utility functions onto well functioning AIs') into your giant scary conjunction, instead of updating, when contradicted. That's the definite sign of rationalization. It can also always be done no matter how much counter argument there exist - you can always add something into scary conjunction to make it happen. Adding conditions into conjunction should decrease it's probability.