We say our battery's 'dying' or the site or something's 'dead' or 'live' or 'alive again' though - post mortem makes sense in that case, I understand the objection but I think you have to object to the rest too.

We declare an "incident". After it, you review the "incident". The site might not have even "died", but you still have an incident.

I agree it makes more sense, from first principles as it were, I'm just saying 'post-mortem' is consistent with other usages, so if we don't like it then we probably shouldn't like 'the server is dead' or 'the site is on its knees' etc. either.