Agree that "type-safe" is an awkward term, but I'm not quite happy with "more obvious" as a way to replace it.  I don't think "type-safe" is entirely inaccurate, because when you try to call a function from a protocol on an object that doesn't satisfy that protocol, you'll get an error that is not really dissimilar from a "type" error.  In clojure, protocols do seem to me to be a mechanism for providing "type safety".

So... I wouldn't mind changing the wording here if we come up with something that we agree is better, but I don't have any great ideas yet what that might be.