Lavinia is a potent hoser, but if shes intended for Standard play, its not abundantly clear just what shes supposed to be combating
As another of the shows main characters, itd make sense for Aang to get the same treatment as these two
At the time, there weren't many decent meta cards, and only cards like Kaiju and Swords of Concealing Light that weren't general-purpose cards that could fit into any of his decks, or one-hit wonders like Lightning could deal with them
And of course, you can just flash the creature in as a fail case thats actually fine in many scenarios
Cards like Abeyance might hit only a narrow selection of spells, or only limit a single player, but Permission Denied trades in both of these weaknesses for a much higher barrier to entry
There are quite a few utility cards that have extra chances to go up