After the alliance got the wintergrasp today i was doing some quests there and i end up fighting a Blood Elf Paladin.
From my experience here and on retail (yes i play there too) you can't teleport inside instances, BG's or any other place if you are in queue cause on combat, and this player simply vanished with 2% HP left to kill him.
Since proving the use of teleport Hack/cheat with SS is Hard the staff should monitor this player to catch him righthanded using the hacks.
Using Hacks/cheats ruin the game. If you can't deal with the battle don't start it.
If he had used "leave wintergrasp" i would lost his target and that didn't happened i still had him on target.
Was it near the fortress? You wont lose target if the target is still near.
But unless you got some better proof than "he did it and it wasn't the thing you all think it is" then it's a dismissed report.