That was 100% the tanks fault and the other BLM was a complete scrub. If you use quelling strikes there's nothing else you can do bar using the sit emote. The fact that you dropped all that power on the second boss and STILL fought for aggro says it all.

I would say that aggro is always 100% the tank's responsibility, BUUUT do use your aggro dump just so they have nothing to fall back on but their own incompetence.

Or you can be a monk at which point, tough titty for them