I don't even know what is and what isn't a pun anymore.
You could say it's what this project does.
I've been looking at newer languages recently, and I see a lot of promise in Nim -- which renamed itself from Nimrod after users warned about what it connotes. Rust could take a cue.
And I don't think I'm alone.
It's just a name, nobody really cares about rusty nails and rust in tap water when discussing Rust the programming language. And by nobody I mean nobody in the statistical significant sense.
It's really bikeshedding.
You're right that no language's name is perfect and immune from bikeshedding; however, the psychophysical mechanism of disgust works at a far deeper, extra-rational level than other negative traits. "Rust" evokes it, pythons don't.