[lorenzhs]

While I cannot claim personal experience in trademark law, the US Patent and Trademark Office's website is pretty clear here. Quoting from https://www.uspto.gov/page/about-trademark-infringement:

> To support a trademark infringement claim in court, a plaintiff must prove that it owns a valid mark, that it has priority (its rights in the mark(s) are "senior" to the defendant's), and that the defendant's mark is likely to cause confusion in the minds of consumers about the source or sponsorship of the goods or services offered under the parties' marks.

Note the last bit, "is likely to cause confusion in the minds of consumers about the source or sponsorship of the goods or services offered". Canonical's IP policy requires removal of all mentions of the trademark, even if they do not meet these requirements.