One chestnut from my history in lottery game development:
While our security staff was incredibly tight and did a generally good job, oftentimes levels of paranoia were off the charts.
Once they went around hot gluing shut all of the “unnecessary” USB ports in our PCs under the premise of mitigating data theft via thumb drive, while ignoring that we were all Internet-connected and VPNs are a thing, also that every machine had a RW optical drive.
Banning open source because of security concerns is the opposite of what they should be doing if they care about security. You can’t vet proprietary software.
It’s not about security, it’s about liability. You can’t sue OSS to get shareholders off your back.