That... is not a restriction on freedom 3. You could complain about your inability to use the rust name for anything you want but that is not the same thing as your ability to distribute modified versions of the software. It is also fairly standard practice for foss software to restrict the use of such trademarks. For example, Gnome does pretty much the same thin. FreeBSD as well. Libre Office also has similar restrictions, although they are defined more nebulously. It is not clear to me what usages are allowed with the Linux trademark but they certainly do restrict who can use it and for what and you must get permission before using it. See also, about trademarks in FOSS: https://www.lexology.com/library/detail.aspx?g=9d96e1bf-bced-48f7-b5b4-ee561e7a9348

The software is free. The trademarks are not. The four freedoms are about the software and not about trademarks. You could fork Rust and call it Corrosion, just like people have forked Firefox and called it Waterfox.