I recall that quest before I rerolled (thanks, Kira). Anyway, I was fully Guardian spec'ed and a level or two above the quest. I did absolutely fine until they popped an enrage buff, thing is...the buff displayed about ten times on their unit frame. Judging by how hard they started hitting, I think I believe it. My fully tank spec/geared Guardian went from 40% to about 5% in a matter of seconds.
When I played JK, I leveled with a Consular and very nearly had to call her in for that. My only advice would be to pop a stim, carry a medpac or five, and hope for the best. If there are multiple stacks of the buff, I would inquire via ticket. I got a copy/paste response though.