@GossiTheDog The systemd change would have sealed off the ssh attacker vector. But liblzma is linked into plenty of other libraries. Just using rdepends even python,tor has a depend on it. So they could have still had value in alternate attack vectors, just not ssh which may have been more universal.
Heck libxml2 depends on liblzma5, so there are even more attack targets like postgres, ruby, php, etc
Kind of a waste to rush, but it may be why they added a plugin system for additional payloads.