You are wrong, SMF 1.x is still supported, so it was the latest version.
Um, just because something is still supported, doesn't make it the latest version. That would be like calling XP the latest version of Windows.
To be precise, if something is supported, then that means all security vulnerabilities should be fixed.
So it is the latest, in the terms of being most patched, version from 1.x branch.
And Microsoft is a
very bad example of how to fix security vulnerabilities, that company is fucked up beyond compare.