Secure boot was only recently added in v2.2.
And every (non-Apple) x86-64 PC and PC motherboard since the release of Windows 8 has shipped with Secure Boot.
10s if not 100s of millions of shipped systems predate that by many years such as every Intel Mac, Itanium systems from both Intel and HP, etc.
I thought Intel Macs were just EFI, not UEFI. And according to the FAQ, this distro is designed for x86-64, not Itanium. I understand Windows 7 Service Pack 1 for x86-64 supports UEFI, but did most Windows 7 PCs come with UEFI pre-2.2, or did they come with legacy BIOS?