perlrun seems to indicate that -Ci makes your original nit technically incorrect. Though, the phrase "in the current file scope" (which is not present in my copy) calls into question this implication that seems to be clearly made more than once away from that phrase (and indicates the possibility of a rather bizarre effect for that command-line switch).

I don't find evidence of support for globally imposing a default non-UTF-8 encoding on streams. I find that a surprising lack and have seen others express similar surprise more forcefully.