While I consider the behaviour described by the OP to be despicable and dishonourable, I recommend to my friends that they start in solo or private group so as to avoid such behaviour; basically get themselves out of the starter systems before switching to open.
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Mind you, if someone wants to supposedly role play a psychopath and blatantly murder CMDRs who in the game's lore are FELLOW MEMBERS OF THE PILOT'S FEDERATION, it's about time, indeed long overdue, that Frontier implemented appropriate consequences. If people want to seriously role play such rubbish, antisocial characters, then it's about time that their continued membership in the Pilot's Federation is revoked as a consequence of that (with commensurate impacts on where they can safely dock, trade etc). After all, if we were seriously roleplaying this, that very membership would come with an expected code of conduct as part of that. Piracy of fellow CMDRs is one thing, but blatant murder of a clean CMDR, a fellow member of that federation, noob or otherwise, is another thing entirely. If we're really serious about roleplaying this stuff that is......