Earlier quoted context omitted.
then its a badly written headline
Well I think it still is a correct headline. In a linux distro, when it "support" a package means that you can contact its maintainers for help (bugs and etc) on the package. So the headline means that RHEL won't help you to install LibreOffice. There are always other way to install it though.
Not to mention, sometimes it's a pain in the ass to install an unsupported app like a compiler or mail/ldap/web server.
And if something goes wrong and you're not using the supported version of the supported package, you don't get support. (Which is how it should be I think)