Does your link to the first thread imply that you believe securing one's bitcoin (and realizing its unique benefits) is ultimately a futile venture, especially in the presence of an adversary of advanced intelligence?

Yes, that looks likely to be the case.

To the second link, I guess you mean to imply the monetary policy of Bitcoin is ultimately flawed due to its deflationary nature?

That's part of it. If decentralized cryptocurrency is ultimately good for the world, then Bitcoin may be bad because its flawed monetary policy prevents or delays widespread adoption of cryptocurrency. But another part is that cryptocurrency and other cypherpunk/cryptoanarchist ideas may ultimately be harmful even if they are successful in their goals. For example they tend to make it harder for governments to regulate economic activity, but we may need such regulation to reduce existential risk from AI, nanotech, and other future technologies.

If one wants to push the future in a positive direction, it seems to me that there are better things to work on than Bitcoin.