I agree with what the others have said.
In the "normal" timeline, the functionists didn't have the time to spend analysing Rung, so they simply gave him a throwaway title that enabled them to pretend that their philosophy was still valid.
However, in the "darkest" timeline, the Council has had another 4 million years (no war remember) to torture and analyse Rung to determine what it is he is.
I don't think James Roberts would have made that coda one of the final acts of the issue if Rung was simply an ornament. And the response of Darkest Timeline Rung makes me think that there is more than what has been revealed.
Without checking back issues, I don't think Rung has ever answered the question of what he transforms to, rather he's simply allowed his alt mode to be used for a purpose (club) and said what others had called him.
Based on what we saw last issue, I like think normal Rung's been deliberately evasive on the topic, because he knows the true nature of what he is and knows that it will have a significant implications for the crew of the Lost Light, and possibly all Transformers.