The guard can be generated correctly, or it can be generated incorrectly (shifted). If there is no normal guard and no shifted guard, you can freely pass through.
If I understand correctly, IMO it is better to correct the item because the interpretation is ambiguous (see my previous post).
"Absence of a normal guard" or "absence of a shifted guard" is the same thing: "absence of a guard." The item will be shorter and clearer.
5.6.3. In the absence of a guard, free passage from one zone to another is allowed.