Yeah I'm generally a big fan but that one is a bit obscure - according to this [0], it's just the incongruity of trained professionals in mortal danger using a childish nickname for the thing that's about to destroy them.

[0] https://www.cbr.com/the-far-side-confusing-comics-like-cow-t...

I think it's simply out of fashion. E.g., "Don't mess with Mr. In-between" is a line from the 1940's song "Ac-Cent-Tchu-Ate the Positive." It's addressing abstract entities in a personalized form, which --I assume-- is a style convention commonly understood at the time.

https://www.youtube.com/watch?v=5Qk9o_ZeR7s

https://en.wikipedia.org/wiki/Ac-Cent-Tchu-Ate_the_Positive

I learnt of this song through the fantastic series "The Singing Detective."

Those only smart enough to think of our local star as "Mr Sun" perhaps should not be piloting craft in its vicinity.

Children's song lyrics I heard growing up.

Sun, sun, Mr. Golden sun, sun shine down on me.