We're all just customers here, so if you want some sort of official response, you'll have to contact Support.
That being said, I wouldn't count on it. Being a registrar isn't their main business, and the .us setup may not make sense for them to jump into. For one, .us domains can't use proxy registration, which may make it unappealing for them to support.
Like you, I have some .us domains, but not registered here, even though I'd like to.