While I can't see "Boeing" (as a whole command structure) can be blamed for his death I do see the possibility of some corrupt person in a high position fearing what he had on him personally and ordered a strike against him.
Boeing is also deeply entwined with state/political entities with a strong vested interest in preserving the status quo who may not be squeamish about direct action. Against the general backdrop of Boeing’s woes, suiciding a whistleblower is low-hanging fruit. Who knows. Maybe he has a deadman’s set up.
The problem with this whole "he totally didn't kill himself" thing is...okay, so how did they kill him? Because you can't just put a gun in the hand of an unwilling person and force them to shoot themselves without leaving evidence.