I think that last paragraph you quote needs the following extra bit of context:

To clarify, we can’t use any philosophical difficulties that would arise if minds were copyable, as evidence for the empirical claim that they’re not copyable. The universe has never shown any particular tendency to cater to human philosophical prejudices! But I’d say the difficulties provide more than enough reason to care about the copyability question.

... because otherwise it looks as if Aaronson is saying something really silly, which he isn't.