Recently, there was some confusion as to why a single-use tag without a tag wiki wasn't auto-burninated after six months. It was later discovered that as someone made a rejected proposal for the tag wiki, a blank wiki was automatically created by the Community user immediately upon edit submission, for technical reasons.
Tags with only one question are intended to be burninated after six months, unless they have a tag wiki (i.e. a community consensus as to what the tag actually represents). But since the proposed edit was rejected, there is effectively no consensus as to what the tag means, and should therefore be eligible for burnination. Also, a blank tag wiki created by the system for technical reasons is effectively the same as no tag wiki: the system even treats it as such since the notice on the tag info page that it has no wiki still continues to show up.
As such, tags only being used by one question with a rejected tag wiki proposal should be eligible for burnination. In other words, a single blank wiki created by the Community user shouldn't prevent it from being burninated.