I dunno, gluing usb’s in a super sensitive environment like that is actually logical; on the disc drives - they could disable autoplay as well though removing or gluing them closed would be preferable. USB is just such an easy attack vector where the individual plugging it in may not have skills themselves - it might be easier to bribe cleaning folks for example - or inject a person into a cleaning team. Ideally they would attack multiple nodes of your target’s network via as many avenues as possible; which makes the network and vpn thing just silly indeed; perhaps they were waiting for someone to try something with excellent infosec / firewalls / traffic shaping. yeeeeah lol.