I think you are right, in that rust did not invent non-nullable references. But I do not see a problem is someone claming that they like that on a language.

I did not read the parent comment as "rust invented nun-nullables and is great", but as "rust, for example, removes the class of problems this way...". I think its neither helpful nor realistic to require every mention of a feature to be backed up by a proper research into who invented in when.