The policy is what you would expect from a journal that is effectively run by volunteers. While the publisher has paid employees, the editorial board in charge of the journal itself seems to consist of volunteers.

When you have a volunteer organization, the impact on people's personal lives is one of the main factors driving decisions. You try to avoid getting involved in somebody else's controversies, as the impact is almost always negative.

From that perspective, the policy seems clear. The authors are responsible for their papers. If someone else claims that a paper should be corrected, they are free to write a paper of their own. That way no volunteer has to take responsibility for someone else's claims.