Is abusing the Dungeon Finder or the RBG system a bannable offense?

Some gankers and world pvp-ers abuse the porting system of DF/RBG to avoid being killed.I want to know if i can report them,or is it "allowed" here.I have screens of about five porting instantly,then appeared a bit later with the deserter debuff.And obviously continued killing lowbies thinking that i left the area.(leaving a bg/instance after 2 minutes is a bit rare occasion imo).One person did this repeteadly to avoid being killed.