"encourages" true piracy and not pointless murder.
hmm... How about this? If you submit to an interdiction you are immune to pvp fire for a set time as long as you stay at 0 throttle and keep hardpoints stowed. During this time, "negotiations" can take place. After that time, anything goes. Psycho murderers wouldn't much like it, but to be blunt, those are the kinds of players everyone complains about, yes?
Still a rough idea - needs refining.