Answer to the question asked by the OP: Yes, it is.
PvP in no way means that it should be honorable, it simply means that that Player vs Player interaction, including combat, is possible at all times. Take into account how people can be ... in the internet ... being anonymous and all ... Yeah, that's a risk you are either willing to take, or not. Regardless the outcome, people will nto have my sympathies on this matter.
In short: If you don't like the PvP part of a PvP realm, re-roll or migrate.