RDF Teleporter and WPVP. Is it allowed?

There's this guild on Horde Side called "The Dudes". They que RDF and then go around the map and "do WPVP". Each time they are about to die, they just enter RDF by teleporting in as they are technically in a RDF.
Is this allowed? Especially for rogues and hunters who can easily get out of combat and teleport.
also, somehow they enter the dungeon from ons place and then when they come out they come out in a different spot.

How is this fair to everyone else? You fight a rogue, he is about to die and then he vanishes, enters dungeon and 3 seconds later he is back full HP with priest bubble, pala sacred and hots.