A story or experience can have a "message" the same way it might have a "moral". In fact "moral" is often defined as: the message conveyed by a story.
"Example" would have been a poorer word in its place.
"Babbage's message" made the title shorter, but also misleading. A complete title of "Babbage's heart-warming" would have made it even shorter, but I hope you're not advocating in favor of that!
Jim did not write a letter. He was the "author" of the sentiment (according to the speaker) by the way he lived his life.
are not identical. The former is a personal article or note from Babbage.
I got down voted for exactly what zeteo said...
and "A message from Babbage's life for the middle-aged"
to me both titles sound elegant but the former is misleading and the latter is correct.
The title is not trading ambiguity, it is just misleading.