As I read it, character set support isn't that interesting to him right now, and he'd rather focus on other things. Everyone keeps treating it like this version of the language is the final one. Of course it's going to constantly gain new functionality.
If that had been my impression I'd never have posted anything on this rather boring topic. What made me think it might be a permanent design decision is this extract from the Arc intro: "[...] it doesn't support any character sets except ascii. Such things may have their uses, but there's also a place for a language that skips them"
The problem is that it's left open to interpretation. Sure, he said Arc is a work in progress, and everyone gets that. The problem is knowing what's on the table for change, and what's not.