A. Most people dismiss an actual conspiracy to murder a whistleblower witness as a conspiracy theory automatically. Such a cliché seems possible. Remember, Boeing is run by MD dickhead bros who traded in camel fucking magazine covers.
B. He wanted additional scrutiny on Boeing, and was willing to die for it.
C. Friend is seeking attention.
It will require honest and diligent investigation to be sure it was truly suicide because none of us know from afar. C seems most likely.
I'm finding the immediate "it was an an assassination" rhetoric gross and unproductive here, because what it's dismissing is a very real problem: becoming a whistleblower tends to ruin people's lives between the media scrutiny, the legal scrutiny, the career jeopardy and being in and out of court rooms. Marriages breakdown, and people get depressed or develop substance problems.
"He was assassinated" is just casually ignoring the fact that Boeing can kill this man dead completely legally through the normal shitshow which is the legal wringer whistleblowers get put through.
His lawyers came out almost immediately claiming he seemed in good spirits. Perhaps this was a superficial assessment or he was hiding his true feelings.
Like I said, wait until the investigation is complete because we don't know. It seems like the friend and media are grabbing attention rather than doing anything constructive.