how can a player have a card rescinded when you can't retroactively punish a player?

[Son of a Gun]

In one case the ref saw it and deemed it a punishable offense, and then the offender gets to appeal the refs opinion.
In the other case the ref also saw it and deemed it non-punishable, but then it's not up for review.

Aren't the two events equal?

[eastgermanautos]

[barrybueno]

http://www.youtube.com/watch?v=bJX3F3XqL9c

[pjlincs]

[Son of a Gun]

up for review and the other not?

[Son of a Gun]