If you want a pause button rather than a quit button then may I suggest that when you press pause, your ship acts like a ship on autopilot so that if you are near a station, it moves away to a safe distance and awaits further instruction, if you are travelling from a to b, it travels in that direction at the slowest speed possible and either saves and quits (in both cases) if no one else is around or circles when close to the destination, if in a battle, it will be in a stalemate with other npc ships in that the shields will take a few hits but neither ship will deplete the shields, if against another player then it will send a message saying that the ship is temporarily under npc (or autopilot) so that the player can decide whether they should continue the fight against the now npc controlled ship or wait for the player to return or leave.
My suggestions are a way to stop people who are in trouble to remain in trouble when they return (unlike logging off) and therefore prevent it as being a get out clause. It also stops players who are safe to remain safe by moving away from a potentially dangerous area like above a pad (as you will be killed for loitering)- you may see this as a way to leave the station safely rather than with skill but the same already happens with those that cheat by logging off and then back on and by leaving by pausing, your ship will be scanned and fined if carrying something that it shouldn't (unlike if you left using your own initiative).
Wow. Returns are free on the internet, don't you know?