> Some of the provided tarballs are riddled with old vulnerabilities
Are you sure you're referencing the current stable version of the LFS book (8.0)? As noted elsewhere in this thread, there was a Live CD version of LFS which hasn't been maintained for several years, but the main book project, along with the ancillary BLFS (Beyond LFS) and ALFS (Automated LFS) are very much alive and well. LFS 8.0 gives you glibc 2.25, gcc 6.3.0, and a 4.9 kernel. If you want bleeding edge, the development version of the book is updated when upstream source packages are released.
> Does it support SATA and UEFI boot disks yet?
LFS has supported SATA ever since it was available in the kernel! There's also nothing preventing you from building a UEFI capable LFS install, provided you setup the BIOS and grub properly.
> should not be used for building a secure, general purpose system.
Why not? LFS is more than capable of providing secure, general purpose systems -- desktop and server.