The question I’m trying to answer is who promised what, where was that published, and when was it published. If a squirrel promised me 10 years of support, that’s different than a CentOS maintainer making that same promise on the wiki.

The 10 years of support on CentOS 8 was published on centos.org's wiki:

https://web.archive.org/web/20201101131417/https://wiki.cent...

Red Hat's explanation was something along the lines that it was a wiki and not guaranteed to be accurate? I don't think editing was open to to people outside of the CentOS org.

I could completely see how one could make decisions based on that date, but I can also see how doing that could backfire. As always, a plan b is valuable.