I know your pain. I myself and a few other random people I met along the way have been farming these since release. These situations with the griefing made us really hate Kun-lai and Jade forest in particular because we always knew that no matter how nice some guys sounded, there was always 1 that liked to chain taunt and get help with a knockback. Fortunately after a few days of farming I finally got my direhorn, and how i got it was quite satisfying.
Me and my group were at Kun-lai, preparing for the worst and spamming our macros to try get the tag, it spawned and we got the tag. We all knew what was coming so me and a fellow druid starting taunting and typhooning it up the hill away from the cliff. Even at 5% these idiots were still trying to taunt with no success. The warbringer died and hey ho a mount dropped, and i won. I immediately mounted it and lol'd at everyone of the morons that tried to steal our tag. Im still with the group that helped me get this and am passing on every mount. I have mine, and will get the rest when these arent so mainstream. But I really cannot believe how immature some people can act over a mob... I know it drops a mount but seriously... That kind of behaviour just gives you a bad name.
I have already sent a suggestion to blizzard to make the warbringers untauntable and unknockable, and even mentioned it to a GM. Even move them to new locations, but this would probably take time and it wont change the chain taunting.