This was something that popped up in my head when I was going for a walk.
Looking back at the 40 years box set, I was actually surprised to see "Me Claudius" was included since Jerry Nelson did Elmo's voice (unless it was just for the sake of including the first Monsterpiece Theater skit).
I'll admit, this is one small issue I have with Sesame Workshop. I can't speak for them obviously, but while they seem to have no issue with uploading/releasing clips that contain guest star monsters or early Big Bird (and possibly Snuffy; I think I recall seeing Snuffy's debut on Sesamestreet.org, but don't count on it), and at least ONE clip where we have the green Grover (first and last skit), as soon as it's a pre-Elmo clip? Nope nope nope nope! We can't confuse da children!
At least, that's what I've honestly gotten from them, considering we've only seen one pre-Elmo clip where he speaks given a commecial release.