Oh my, the silly RP vs PvP discussion again.
Now, it's perfectly alright to question how viable a RP PvP server is, in terms of cost of enforcement of the ruleset, if taken seriously, vs the number of players it brings in (and who would quit the game if the RP ruleset were dropped). But that is a decision to be taken by the company which runs the game.
If the company decides to establish a RP PvP server, it signals to players that it is willing to enforce RP rules on that server. This includes (surprise!) naming conventions. Rolling a toon with a non-RP name on a RP server is a bit like public drinking in the US - you may feel morally entitled to doing it, and you may get away with it on most occasions - but if you are caught, none of this changes the fact that you violated the law.