I will kill my room mate if he does that to me.

well, if the player taunt u while you have less health point, maybe it means you should be the one going offense because its safer for him.

are you turtling most of the time? its a known fact that in ranking matches, everyone is going for the win.

Imagine Zangief with less hit point than sakura, and znaigef turtling on the corner waiting for sakura to jump in and eat LAriat? no way..i will Taunt the gief definitely to ask gief to go offense.

going back and taunting you isn't no sportmanship. if its casual people don't mind losing, but if its rank match for BP, playing the wisest option is a must.
but anyway quitting in a middle of the game will not affect anything.. just less and less players will play with you in the future..

its the same with Dota ( if you play dota ) .. you can't leave the game when your opponents drags the game, its just a smarter choice for them to come fully equipped into your base.

just an observation not a judgment, i played with you in Outpost before i think?