This is a poor take. People don't find themselves in this situation normally and we should not be expecting them to have TV-murder-mystery style hypervigilance.
The tv-murder-mystery plot where Boeing killed him and he told ONE friend is much more likely?
Anxiety, PTSD, and a hand gun. This is a recipe for a suicide attempt that succeeds from a purely statistical point of view.
Also, it is of course possible, to plan suicide and still tell people it won't be suicide. We all lack the details here. But since Boeing is involved with military and intelligence work who do not like traitors(whistleblowers) in general and have the expertise in covert murder, I think murder is a valid theory that should be really investigated by a neutral agency.