I noticed that immediately on the home page. The author suggests installing and running some sort of python package to verify the pdf is harmless. That sort of makes sense, until you realize that installing a random python package and running it is exposing you to far more risk than a opening a pdf ever will.
Have you looked into pdf vulnerabilities? I'd say they're about equal
It makes sense to me that you would want to hide from your ISP and whatever service you're using that you're using Tor.
From the Tor wiki:
> You -> X --> Tor --> X
> No research whether this is technically possible. Remember that this is likely a very poor plan because [#You-Tor-X you -> Tor -> X] is already a really poor plan.
The guide recommends using a VPN over TOR in "specific cases", for example "when your destination service does not allow Tor Exit nodes", and for "VPN over TOR over VPN" they say it's not recommended because "it is just VPN over Tor but slower".
Although, I didn't expect much considering the guide is created by the same people who made privacytools.io. Another hilarious site.
This suggests to me the author is giving advice based on paranoia rather than technical knowledge.