The reason the Safe C++ proposal wasn't mentioned is that it came years later. =] I'll see if it makes sense for us to update that section a bit, this probably isn't the only thing that we should refresh a bit to reflect the last few years of developments.
FWIW, the biggest challenge with Safe C++ is that WG21 rejected[1] that direction. And it was developed without building a governance model or way to evolve outside of WG21, and so doesn't seem to have a credible path forward.
[1]: FWIW, some members of WG21 don't agree with this characterizationp, but both the author's impression and the practical effect was to reject the direction.
FWIW, the biggest challenge with Safe C++ is that WG21 rejected[1] that direction. And it was developed without building a governance model or way to evolve outside of WG21, and so doesn't seem to have a credible path forward.
[1]: FWIW, some members of WG21 don't agree with this characterizationp, but both the author's impression and the practical effect was to reject the direction.