They may have done a poor job of explains thing, but they are right. Secure boot is a system that every manufactured computer in the last 5+ years has support. The only reason you can install anything but Windows on most PCs is because the manufacturer let you, but they could take it away in an instant by requiring secure boot and only allowing Microsoft’s signatures to boot an OS. Valve could have done the same thing if they chose. That’s basically how the XBox works these days, and it wouldn’t surprise me if the PlayStation is the same, since it is x64 as well.