If a spell, ability, or effect states that a player can do something only "any time they could cast a sorcery," it means only that the player must have priority, it must be during the main phase of their turn, and the stack must be empty. The player doesn't need to have a sorcery they could cast. Effects that would preclude that player from casting a spell or casting a sorcery don't affect the player's capability to perform that action (unless the action is actually casting a spell or casting a sorcery).
Je suis d'accord, j'ai trouvé ça plusieurs fois un peu troublant, mais cette expression veut dire "pendant une phase principale de ton tour alors que tu as la priorité et que la pile est vide".