On that site the author is the same one as listed on the infosec article, and they claim he's a researcher for ISI.

I am not sure how you get from the PDF to the confirmation. The first page of the PDF says it is from “Infosec Institute” and “Darmawan Salihun”. If you want to show plagiarism, should you not be linking to a version that has the same contents but with different authors?

Darmawan Salihun is the author of both and according to his LinkedIn page:

BIOS/UEFI Security Researcher InfoSec Institute June 2012 – Present (2 years 3 months)

Plus the OP's article was published before that PDF (January Vs. Feb).