How does Edward Snowden acquire a laptop or phone in a way that he can trust it? I don't think it matters what protocols and applications he uses: he does not enjoy privacy.
I order to get a device that is not explicitly compromised with custom targeted malware one could: take a walk, enter a random shop, buy a device. Now you only have the standard malware that everyone gets preinstalled on their devices.
How to keep it free of custom targeted malware? That is another question!
With a target like Snowden who is under constant surveillance and lives at the whim of his host country, he could expect that any off the shelf hardware he bought would be immediately compromised. His hosts would just make up some bullshit reason to part him from the device for several minutes and do an evil maid attack. Or from afar his hosts or another country's actors could exploit undisclosed vulnerabilities in his device's wifi or bluetooth layer that they have in their toolkit.
Two key words in your comment are both spectrums: trust and privacy.
Most people implicitly trust their hardware more than Snowden does now -- they overestimate the security from the factory and he probably has better expectations of the likelihood of hardware compromise.
On the privacy spectrum, one point is how much privacy you think you have, and the other (unknown) point is how much you actually have. Similarly, I think Snowden's situation and prior experience helps him more accurately understand where those points are; the rest of us are up on the first peak of the Dunning-Kreuger chart.
How to keep it free of custom targeted malware? That is another question!