Citing a ruling pertaining to a court case about physical typesetting equipment that predates the decision which extended copyright to software generally..seems a bit of a reach...and doesn't actually address the issue of what permitted use is in regard to the _software_ Canonical is providing "all rights reserved".
Even granting you that court case... the copyrightability of digital typography is even more complex than you realize. That court ruling basically makes typefaces uncopyrightable as artistic works in the US. But, because the US is a signatory of the Berne convention... US courts must uphold typography copyrights from other jurisdictions that allow then to be registered as artistic works... effectively mooting that ruling as other countries allow fonts to be copyrighted.
If I had clear license to _use_ the font software and took a screenshot of that usage or printed a document from a computer program _using_ the font software...things would be fine. But there is no EULA that tells me what I am allowed to actually do with the font software such that I can take a screenshot or print a document rendered with the font software in use. Certainly installing and accessing font software with other software programs is not automatically fair use.