You might get Chocobo on the Loose! first, instead of this quest. If so, you want to get Chocobo's Wounds but you don't want to finish Chocobo on the Loose!. To by-pass Chocobo on the Loose!, Talk to Brutus again, talk to Silver Tail, and than talk to Brutus once more (You may just need to click Brutus again to get Chocobo Wounds quest -- check your current Jeuno quests log to be sure you received it). He should ask you a question if you want to ride a chocobo.