The problem is not that you're misrepresenting the font as copyleft when it isn't. The problem is that you simply don't have a license to redistribute the font at will: merely uploading the font to a public GitHub repo violates the license.
You have the right to serve the font from your webserver, and link it into your site via CSS. You absolutely have not been granted the right to redistribute the font in any other manner.
If you post a page on your site with "Like this webfont? Download here!" and link to the same URL that you are using to host the font for display purposes, you'd be violating the license. It's the same exact URL, but you can't post a clickable download link to it. It's not allowed, and if you do, they can at a minimum yank your license to use it at all.
https://processtypefoundry.com/help/base/webfont-license-agr...
Editing to add: trying to solve the problem by adjusting your LICENSE file is roughly equivalent to the "I don't own this!!" disclaimers that people put on YouTube uploads. They get DMCA'd just the same.