I talked the taru BRD, told him I didn't recall anything about his music, then talked to everyone else in the bar. Satisfied, I left and headed for Jeuno. But when I got there, Ruslan wouldn't give me the quest. I figured I had forgotten something, so back to Windurst I went. I had to talk to the BRD again ( and told him his music was unimpressive ) and then one more time for him to actually trigger the quest.
If you get it unlocked, the BRD will ask you to "please forget what I just said." Anything less means you'll be coming back to Windurst after you realize Ruslan isn't interested in you.
All in all, a decent flute for BRD, and it sells for 100k on Sylph. I've been levelling BRD myself, so it was nice to need an instrument I could go quest instead of purchasing on AH.