I never figured that out, I think Fading Memories would remove the Bard from the first in the agro list and the rampage tank would get themself in the third place. As soon as the Bard dropped the mob on the raid and switched to wide area buffs, they slotted back into that empty spot and got splatted. It always felt like you'd drop FM and clear the spot, but would have a reservation on that spot in the agro list. Didn't really matter, you'd single pull a boss back to camp, die, and claim the reward when the other 70 folk finished killing it. The interesting part of the fight was always the pull. The rest of it was just tank and spank.
I'd fairly regularly drop a mob on the raid, fade and still be on rampage. Bards were not bullt to be rampaged on.
Vindi was still a hard pull, Bard tricks didn't work on him. (When he could quad for your entire life, not so hard when you could take 15 quad hits in a row and still be alive)