Les règles disent que les capacités "If you do" ne regardent que le fait que tu payes le coût (ici le coût c'est exiler le Gamekeeper), peu importe que l'action soit ensuite remplacée.
117.12. Some spells, activated abilities, and triggered abilities read, “[Do something]. If [a player] [does or doesn’t], [effect].” or “[A player] may [do something]. If [that player] [does or doesn’t], [effect].” The action [do something] is a cost, paid when the spell or ability resolves. The “If [a player] [does or doesn’t]” clause checks whether the player chose to pay an optional cost or started to pay a mandatory cost, regardless of what events actually occurred.
Un exemple parlant, toujours dans les comprules :
Example: Your opponent has cast
Gather Specimens. You control a face-down
Dermoplasm. You turn Dermoplasm face up, and you choose to put a creature card with morph from your hand onto the battlefield. Due to Gather Specimens, it enters the battlefield under your opponent’s control instead of yours. However, since you chose to pay the cost, Dermoplasm is still returned to its owner’s hand.