Although that being said, I wouldn't rule this out as being organised by Boeing's management or a major shareholder or something. It is a company in the military-industrial complex.
If the US government pardoned him they’d be doing themselves a massive favor.
Because this time wasn't about silencing him (too late for that), but making an example. And for this, a blatant enough assassination would likely tarnish the image the US government wants to project too much. Going through the courts, making a show of "due process", now that's looking pretty good: "hey journalists, we can't kill you if you babble too much, but we can make you wish we did, and since it's all legal good luck about rousing public opinion about it".
Perhaps he is an object lesson that one should create a "switch escalator".
Perhaps a dead man's switch used in captivity could also potentially make captivity worse and remove what last remnants of hope he has. I suspect if he pulled the switch now then a lot of the sympathy he got for exposing a war crime might go out the window.
There are still lots of angry articles about how it will PUT LIVES AT RISK if it is unencrypted.
The powers that be appear to be walking a tightrope between not exposing their own assets and trying to make an example out of people who expose war crimes while trying not to put lives at risk.