One thing to note is that the man would probably harm, not help, his chosen charity (in expectation).

If it was thought that the charity had encouraged the "really extreme altruism", or if it was simply thought that the charity was the sort of thing that fanatics like that liked, the charity would have serious problems attracting others' work or donations, since most people fear fanatical and suicidal mental states. It would need to refuse the money, and refusing the money wouldn't be enough to prevent serious damage.