If I am on a PVE server I dont want to have pvp enabled automatically ever. Tab targeting or spam clicking during invasions and accidently hitting someone pvp flagged sucks. If I want open world pvp let me enable it by /pvp on. Getting accidently flagged in a cluster of players is never fun.
Its a PVE server, make it PVE and make PVP opt IN not auto in by mistake.