Overlong tweet policy is weird and inconsistent.

The official twitter handling of over-140-character tweets is a little weird to me. To start with, twitter takes extralong tweets fine from third-party clients, but won't let me post them from twitter.com. On top of that, though, when I post in asian characters, it frequently truncates my tweet and makes people click through for the full thing, saying that it's over 140 characters. Is this because asian characters are multibyte, or is there a different length policy for different scripts, or what?