One thing is for sure, that the person who isn't put in the grave doesn't get to bypass the torture or the pleasures of the barzakh (period between death and judgment).
If they were evil, they still get to feel the punishments and if they were pious, they still get to feel the rewards. We can't throw ourselves in the graves after we die. That is up to the family members or the community. But, just because the community neglected to bury one of us, doesn't mean we suffer or we are excused from the trials of the grave.