Ascended aren't immortal. They can be killed by any major wound just like any other descendant. In this case, I believe their 'immortality' is just not dying at a certain age. In fact, I saw an ascended die to an axe to the back of the head. I'm not an ascended expert, though I'm just stating what I know.
About the body burning, the loot stays behind. Once again, I saw this specific ascended get the few items he had on him taken via /search.
They are immune to all potions, healing as well. Not just poison.
And as for the bullying, I don't believe you were there to see exactly what happened before this staff member left, but I was. "you did a **** job," or "get your **** together" is not criticism. That is just being an *******. There was no attempt at all to give some advice or constructive criticism. It was mainly just name calling and making fun of them. I was literally in a voice chat with these people when it happened, furthermore proving my point that everybody, not just the ascended, are toxic.
(Also, no harsh feelings, Chon. Just trying to give my opinion about the topic.)