r/swtor - How do you handle other players fighting to a quest objective?

As in, if a person is clearing the way to a quest objective and is in the final fight before interacting while you are clearing a separate group of baddies, do you help the other player out when it is obvious that the other player has his/her fight under control?

The reason I ask this is that I was doing a bonus series quest on Taris, and encountered another Sith clearing to a quest objective and fighting a elite mob as the final mob before the quest objective.

The player was fighting him as I walked in, I aggroed a separate group in the room that he didn't kill, killed them, and waited until the other player had killed the mob he was fighting (lived with ~75% health left) and interact with the quest objective before doing so myself just in case it temporarily locked him out from completing the objective he was clearing to.

He then proceeded to bitch me out for letting him do all of the dirty work to get to the objective... which he was already doing... while I let him finish his fight that he had already tapped, and finished only a few moments after I had wrapped up my own fight with a group of mobs, somehow feeling that I was a jackass in all of this.

Am I somehow in the wrong? I really don't feel like I am...