Incorrect. The point is that no matter what proof-of-work algorithm an altcoin employs, those who are protecting Bitcoin will rent enough mining hash rate to fuck your coin forever. They only have to rent it for a short period of time, and your difficulty will be so high that it will never produce a block again. And all the money in the chain will be unspendable for a very, very, very long time.
If you are talking about Monero the difficulty retargets at every block, such attack is not possible. Cryptonight isn't very ASIC-friendly so you'll have to spend in real GPUs and CPUs to attack.
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If Monero starts to approach $1 billion market cap (or perhaps much less if the liquidity is very high, which it is for Monero), this attacker will destroy Monero and profit by shorting.
Same logic could be applied at Bitcoin if the bankers decide to kill it as they are the "threatened group" and the only ones with enough resources to mount any kind of network attack.
Incorrect again. Try again to read the "attacker's" blog article.