There is a lot of misinformation here
This is a very poorly written article. However, the current software acquisition process is arcane and built on processes from two decades ago. Additionally the security of the software supply chain is of paramount importance. The XZ Utils situation really spooked the cybersecurity folks in the government.
How a huge, well resourced organization (like the US military) looks at open source will be different from an individual level. Having control and obscurity of the code you are using could be an attractive trade off to the transparency of open source. Not arguing this either way, just pointing out the default pro-open source position of privacy enthusiasts may not apply to all contexts.