I think it means that OpenSUSE is "all of the above"—stability, flexibility, security—because those are qualities frequently attributed to German things/products.
It isn't really a joke in the sense of it making fun of Germany or anything like that.
I think random freezing is one of the symptoms of installing it with Ventoy. Ventoy mucks up one of the installer flags or something like that, so even the wiki indicates it's not supported. (Neither is installing it from the Live tester, if I'm not mistaken.)
The An Hero model!