I addressed it in the first paragraph of my comment above. Let me quote from it here: The theoretical attack argument is indeed "applicable, not just to Algorand and other block chains, but also, more generally, to ANY transaction platform" -- VISA, Mastercard, Amex, ACH, Fedwire, etc. No one disagrees that it is
applicable, i.e., a theoretical threat, to all transaction platforms.
Now, if you think such an attack is an important problem for block chains, then you must also think it is an important problem for all legacy transaction networks. Yet we're all comfortable using our credit cards and bank accounts every day, and for virtually all practical purposes, we don't worry about a "Doctor Evil scenario." Why should we think and behave differently for block chain networks?
Moreover, as I wrote before, in practice, legacy transaction networks (like, say, regional VISA networks run by 100-year-old banks) are easier and cheaper to attack. If the Doctor Evil scenario were a real threat, it would be more profitable for him to target one of the legacy networks!