Seems entirely reasonable for these disclaimers to exist given that while Go is a legitimately open source project separate from Google, it is still strongly as

Seems entirely reasonable for these disclaimers to exist given that while Go is a legitimately open source project separate from Google, it is still strongly associated with Google in people's minds (not too surprisingly considering how many of the core Go team work at Google) and thus it wouldn't be hard to imagine some people getting the wrong idea of this somehow being Google's (or the Go team's) "official" answer to UIs in Go.