I find it amusing that you are one-sidedly complaining about appeals to authority when so many comments, on both sides, in this thread boil down to "my preferred expert is better than your preferred expert".
The difference is that, "my preferred expert" took the trouble to explain his reasoning which I will paraphrase as "Thermal runaway in Lithium batteries."
Upvoted, to me Musk is being a publicity whore and scoring cheap hits over Boeing. I.e. his comments do not help us in advancing our understanding so can only be intended to publicise his own company's products.
Musk being a publicity whore has no relation to the safety of the batteries. The fact they catch fire during normal flight operation demonstrate they are not.
He may well be. I can't say what is Musk's intent. What I can say, is that if Boeing handles their business properly, it won't make much difference what anyone has said or done this time next year.
