The most annoying part of this fight is that sometimes he random switches target even if "off" tank has taunted him. Happened to us several times yesterday. Especially after the 2nd challenge this seemed too happen alot.
When 1 tank gets knocked up into the air the other tank obviously taunts him, but the second the tank that got knockedup lands again, he goes straight back to him causing lots of problems if he is about to do a special ability like the knockback, red circle, teleporting away someone.
about switching target check this http://www.swtor.com/community/showthread.php?t=712283