PDF is a famously (and hilariously) wild document format because it satisfied the need of being able to recreate a work piece faithfully using thousands of kinds of outputs, some of which didn't even exist when the document was created, to ideally arbitrary pixel resolution (see https://www.youtube.com/watch?v=qbCniw-BcW0 for a delightful and informative talk including this topic).

As a result, in one of the modes of PDF you can save the entire font file for every font used by the PDF into the PDF itself, just in case it's not present on the recipient's machine. Costly? Sure! But what else are you going to do if your document uses a super-special font for displaying mathematical symbols or sanskrit or the glyphs of a language understood by fifty people on the planet and Unicode isn't widely adopted yet, having been invented just two years before PDF?

So in this case, the author grabbed a copy of a PDF version of the ad (because those ads are still available online), cracked open the document itself, and found the glyphs for the letters are sourced from a version of the font that was intentionally created to steal someone else's font work because the whole font file is in the document.

In this case, per the link:

> went sleuthing and quickly found a PDF from the campaign site with the font embedded

So, the PDF had the font Xband Rough embedded inside of it.