How on earth does one reconcile this with the fact that Ilya has now publicly tweeted that he deeply regrets his involvement in the board’s actions, and that he has signed the open letter threatening to quit unless the board resigns?

This is a critically important point to hold in mind if the reason for the move seems to be due to safety concerns as opposed to personal malpractice/deceiving the board

Really strange that, while this looks like the most likely reason, it's not really reflected in the language.

Do these explanations seem at odds to you for some reason? The language used in the statement does not say anything about personal malpractice/deception, just that he was "not consistently candid in his communications with the board". It seems entirely possible to me, and indeed probably most likely given what else we now know, that the board is alleging dishonesty re: safety-related commitments he made, or something like this. 

Reading this I can't help but think that we are all capable of so much more, of being so much more empathetic, and of building a much better world in which lives lived like Alexa's are not so anomalous. 

I can only imagine how difficult it has been to grieve such a person and I am profoundly grateful that you have chosen to write this, so thank you. You've ensured that their kindness and care for others will outlive them through those who, like me, have been inspired by their story.