Sure, but neither bcrypt or chess fall into the category of being unprovable, so having a halting detector doesn't help for those situations. The author is mixi

Sure, but neither bcrypt or chess fall into the category of being unprovable, so having a halting detector doesn't help for those situations. The author is mixing up problems that are "hard" in the sense that we know in principle how to solve it but need a lot of resources, versus "hard" in the sense that we genuinely don't know how to solve the problem, even if we had access to infinite resources. Mixing these two up is very misleading and detracts from what is otherwise a well written article.