A 3 word phrase before attacking you should/is not classed as RPing prior to a fight. Should be a little more than that...such as a warning like "Leave here Rogue scum or I will shoot" or something along those lines. Correct they attack Rogues but that's just harsh and not in good spirit to attack straight away.
Give them a lesson in RPing or report it (with proof) if the offender repeats it.