Welcome to fixation, where your definition of "Proton" is colored by
your past experience with the word. Instead, I suggest that Proton
has nothing to do with Proton Mail. This sentence from the article:
"My new Proton is actually an old one I established
quietly with a cash only burner phone while on
vacation several years ago."
which suggests to me that Proton is an account on some public free
email system. Try to substitute "xxx account" for "proton", where xxx
can be AOL, Gmail, Hotmail, Yahoo, etc and see how it fits. For
example, this sentence from the article matches quite well:
"I will continue to use public WiFi and the TOR
.onion connection to Proton to prevent an adversary
from watching TOR entrance/exit nodes."
As to which online email service, it would need to be an online
service that used mobile phone numbers for authentication many years
ago but does not continue to verify the mobile number because Toebbe
switched to email for authentication or removed 2FA authentication
relying on a single login password. Methinks Yahoo or Gmail, from
about 12 years ago, might fit the description, but I'm not sure.
Jeff Liebermann je...@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558