I'm inclined to think he was in league with or blackmailed
by multiple intelligence agencies in various nation-states.
That kind of opens it up a bit. Like any organization, leaving
the keys to the castle in one mans hands would be a mistake.
So if someone hit him out of general principle, when they find
out who did it, perhaps that will trigger a strategic release of info.

I don't put it by either of the agencies to burn him or have him hit.
So it's completely plausible that he was killed. However, if he didn't
also look out for himself.. I mean, anyone working for those agencies
would know that they cannot be trusted. Even the Google leaker was
smart enough to use a deadman's switch, & that may have saved him
at the time when the police raided him.

I'd like to know how his convo with the police was, if he told them about
the deadman's switch. That incident reminded me of the movie Antitrust
and embarrassed Google so much, that I don't think they're even willing
to publicly acknowledge that it happened. If they do acknowledge it then
explaining why they didn't do so earlier should be a challenge for them.
This one is so tough to call, it's just really hard to say with any certainty.