SunOS 4 indeed had an /sbin. I explained this in more detail some years ago.
https://lists.debian.org/debian-user/2019/02/msg00041.html
But it didn't mean static linkage in SunOS either. That is, as someone else described it on Hacker News a few years ago, an "ahistoric retcon". /sbin was for the system binaries (notionally) needed for bootstrap.
When AT&T Unix and BSD adopted it, they coined a parallel /usr/sbin too.
It's not a correction when it's ahistoric. (-:
That version of the explanation of the name of sbin is not actually supported by any 20th century Unix doco. The books on AT&T Unix System 5 (before which, things were in /etc) that actually give an explanation for sbin all say system binaries, or system administration commands; and none of them says anything about linkage.
The "static link" story came from Linux people years afterwards.
https://groups.google.com/g/comp.os.linux.development/c/EKzLcOh9vXQ/m/BpcTkHVLdkMJ
I would not say *nobody*.
JdeBP
Melroy van den Berg