Ultimately the system will need to support signatures which represent not just "I made this" but "I reviewed this", and people will need to set policies for whose reviews they trust, and how many reviews they require for each component.
If reviewers can build up a reputation anonymously, that will make it harder to find the human who needs to be crowbarred, but I'm not sure how you prove you are a good reviewer in a way which isn't gameable.
Alternatively, the reviewers could be well known teams in multiple jurisdictions, such that an attacker would need to buy multiple crowbars and multiple plane tickets.
If reviewers can build up a reputation anonymously, that will make it harder to find the human who needs to be crowbarred, but I'm not sure how you prove you are a good reviewer in a way which isn't gameable.
Alternatively, the reviewers could be well known teams in multiple jurisdictions, such that an attacker would need to buy multiple crowbars and multiple plane tickets.