From technology point of view of a discrete control, opening the bridge will disconnect the traffic across the sides. Is this barrier secure?
It all depends how the entire protection system is run. The bridge will only block access via that land path. What about access is via air or water?
By the same token, vulnerabilities in a computer platform or its underlying applications will not pose immediate cyber threat if it has its own surrounding effective electronic security perimeter.
As professional cybersecurity practitioner, we have to reassure comfort to management rather than just follow text book knowledge to clear all known vulnerabilities. That is not practical to achieve.