It is only counterintuitive because you arbitrarily assigned a different type (boolean, with members you made up) instead respecting that any utf8 character fits the utf8 type.
X is used variously as true and false in Different languages, so why would you assume it means false in a language you have never used?
Well i didn't make it up, but yeah i get your point. I didn't mean that i'd assume it means false, but it's still clearly counterintuitive to use a tick to encode as utf-8 when any character at all will do. A tick has an opposite, an X, a snowman (as in the Rails case) doesn't.
X is used variously as true and false in Different languages, so why would you assume it means false in a language you have never used?