There is plenty of evidence of foul play you smartass. They willingly risked lives over many years and are still currently flying many planes with defective unsafe parts. Going from that to assasination is not a big leap.
Multiple of the whistleblowers and their colleagues have also independently said that their workplace was directly and deliberately sabotaged in order to continue using defective parts.
Yes the last one doesnt really look like a typical assasination but it doesnt matter in the slightest if it was or not.