tl;dr: This is just your typical list of "privacy focused" and "self hosted" alternatives (e.g. use Signal not Facebook Messenger), with some attention-grabbing framing.
Some of the recommendations are pretty suspect, too: how is using Thunderbird for email supposed to "opt you out of PRISM and XKeyscore"?
If the reference is keeping all your messages, and potentially your PGP keys, in "cloud" storage at a PRISM provider it's not particularly hard to understand some ways in which using Thunderbird instead is supposed to help. It's a fair point it's not a particularly satisfying mitigation though.
> Do you realize that page was established in 2013?
No, but that makes sense. The framing would have been much more apt back then than it is now, with the Snowden stuff being fresh.
> If the reference is keeping all your messages, and potentially your PGP keys, in "cloud" storage at a PRISM provider it's not particularly hard to understand some ways in which using Thunderbird instead is supposed to help. It's a fair point it's not a particularly satisfying mitigation though.
The reference is just "instead of Gmail, use Thunderbird" (e.g. https://prism-break.org/en/subcategories/macos-email/). They don't mention PGP in that section at all, though there's a later one about "Email Addons, which does, which is easy to miss (e.g. skipping b/c you don't already use addons).
Their (broken HTML) recommendation to run your own email email server is also suspect, because it's a bad tradeoff. Unless you want a second, unpaid job as email server administrator (with a pager!), you're "protecting" yourself against a rare hypothetical threat (government surveillance) by making yourself vulnerable to a much more common one (run of the mill hackers).
Realistically, they probably should have just said something along the lines of "email surveillance is practically unavoidable," so don't use it for anything you don't want monitored. PGP failed because it's too hard to use, so no one uses it, and any reasonable use of email will mainly involve exchanging messages with some "monitored provider's" servers.
I guess using Thunderbird would get many people away from relying exclusively on the web interface of gmail. Then the next step would be to make an e-mail account at another e-mail provider. Later maybe switch away from gmail entirely.
> how is using Thunderbird for email supposed to "opt you out of PRISM and XKeyscore"?
The mail client may help improve privacy if you configure it to erase data in the server as it is downloaded to the client (POP), instead of letting it stay in the server for a indefinite amount of time (IMAP). If people are going to break into your provider, a empty mailbox would limit compromise.
Some of the recommendations are pretty suspect, too: how is using Thunderbird for email supposed to "opt you out of PRISM and XKeyscore"?