Will he receive a payment for this lecture? If so, I'd hope a donation to a suitable charity is made, given the subject is entirely related to a recent tragedy. I appreciate spreading the knowledge may help prevent a future event, but his profiting personally would leave a sour note to my mind.
On the other hand, hats off to him if he is doing it 'gratis' as a way of highlighting the errors uncovered. After all, he was no doubt adequately rewarded for his work on the inquiry in the first instance. Just my opinion - only ever met the bloke once.