Gilded drake et protection

Bonjour. 

Que se passe-t-il si un joueur lance Gilded drake, cible une créature adverse, et que celle-ci acquière la protection contre le bleu (par exemple). 

La capacité devraient être contrée par les règles, mais elle ne peut pas, donc elle se résoud. Jusque là, ok. Mais pourquoi l'échange ne se fait-il pas puisque la capacité se résoud ? À moins que l'échange se fasse ?

If the spell or ability specifies targets, it checks whether the targets are still legal. A target
that’s moved out of the zone it was in when it was targeted is illegal. Other changes to the game
state may cause a target to no longer be legal; for example, its characteristics may have changed
or an effect may have changed the text of the spell. If the source of an ability has left the zone it
was in, its last known information is used during this process. The spell or ability is countered if
all its targets, for every instance of the word “target,” are now illegal. If the spell or ability is not
countered, it will resolve normally, affecting only the targets that are still legal. If a target is
illegal, the spell or ability can’t perform any actions on it or make the target perform any
actions.