(we probably shouldn't be reviving 5 month dead threads) but I'll throw my 2 cents in here since this is being talked about again.
Lets define the issues being discussed first: There is not enough RP between antagonists and security officers
Roleplay at its most basic level is putting yourself into a certain role or position with motivations, believes, and core values which heavily influences the choices you make in-game. In this case, we're talking about how players act when they envision themselves as security officers and how they act when they envision themselves as traitors. I do not believe people have an issue roleplaying as these roles, you just don't like how these positions interact with each other when players are roleplaying in them. Furthermore, you think that because of the design of our game mechanics, the roleplaying leads most often to violence instead of interactions you consider more valuable like in-game chatting, bartering, and non-violent exchanges between officers and traitors.
So I'll impart my first suggestion here, don't try to force player behavior, incentivize them to act in the way you want. Traitors are still nonetheless violent and intense when pursuing what you consider to be minor objectives, they know that if they get caught its likely game-over unless they prepared by not bringing and s-class or committing 400+ crimes. Security does not know the level of intensity of antags so changing their objectives while hijack/murder/etc objectives still exist will not lower their level of escalation, so antagonists will match this by always being violent even if they have minor objectives. You need to give players rewards for being non-violent.
There is absolutely zero incentive not to be violent in antag/sec interactions (besides being punished for breaking server rules) which IMO is poor gameplay overtime. Officers first need some sort of progression structure that can be sped up by being corrupt, such as being able to get slightly better equipment with space cash (so briberies :)). 2nd, one thing that could be implemented that will also fix a lot of other issues is implementing buyable / choosable objectives instead of handing them out at round-start. Players should be able to choose objectives that match their playstyle. These can even be objectives--like you were saying--that are minor enough that it won't land them in perma, which means traitors get a much more softer start to their round which won't merc them for a minor mistake.