Then again maybe the quality of Lincoln's literacy defies it.
I think so. My first thought reading this output is that I should ask the LLM to first write in the style of Lincoln and then slightly modernize the prose.
This is all just demonstrating the helplessness that's coming to our society w.r.t. dealing with gen AI output. Looking for em-dashes is not the solution and distracts from actually having to deal with the problem. (Which is not a technical but a social one. You can't solve it with tech.)
Yes, the “AI detectives” can be quite annoying, as the comments are always the same. No substance, just “has X, it’s AI”. The em-dashes detectives tend to be the worse, because they often refuse to understand that em-dashes are actually trivial to type (depending on OS) and that people have been using them on purpose since before LLMs.
Mind you, using em-dashes as one signal to reinforce what you already perceive as LLM writing is valid, it’s only annoying when it’s used as the sole or principal indicator.