Nails wasn't the reason why the body stayed to the cross, the reason was love!
The passage "Luke 23:34" shows clearly most people didn't know what they've done (in opposite to Pharisees, who made "blasphemy against the Spirit", what's the one sin which is unforgivable in this life and the next life too, Matthew 12:31-32).
Some of them started to repent timely, other ones will be to frighten when Judgement Day is and they see him again as their Judge, but all of them have to accept the eternal consequences of their decision, which they made in this life.
