Anybody can take the Traveller rules and use them in another setting. To be worthy of excommunication, you need to work within the system to subvert the system. I came up with the following list while planning my next Traveller outing.
1. Charted Space? Your using the wrong chart, bub! Using the canonical Traveller universe is just giving the PCs too much information. I'm going with the Gateway Quadrant, a group of four sectors from Judges Guild. Other options included the two Paranoia Press sectors (the Vanguard Reaches and the Beyond), the Islands Clusters back when it was accessible via Jump-6, or use the map from Dark Nebula. And don't forget the timeless option of using a random subsector.
2. Cantinas full of aliens. Why use a human when a three-eyed reptile will work? Don't limit yourself to the Major Races either. Get GURPS Traveller: Aliens 4 for a lovely mix of minor races, sprinkle in some GURPS: Aliens dudes, and maybe spice it up with one of the random alien generators published in Dragon back in the day.
3. To boldy go where no human has gone before. I don't care how long humanity has been aomng the stars. Somewhere there have got to be some cool planets that humans have yet to visit. What self-respecting adventurer wouldn't want to claim a planet for the homeworld, and maybe name it for themselves?
4. Blow some shit up. The PCs and their archfoes should leave a trail of destruction behind them that leaves Kei and Yuri of Dirty Pair jealous. We're not talking simply fragging some space pirates or shoot-outs at starport customs. Whole planets need to explode. Stars should be set to nova. Heck, someone needs to use a corbomite device and wipe out a whole subsector.
5. More zap guns, please. Shotguns in space are dandy, but no match for a good blaster at your side, kid. And what PC doesn't want a phased plasma rifle in the 40-watt range?
6. Xenocidal War. I'm sorry, but the Fifth Frontier War is as dull as dirt. We need bug-eyed monsters lusting after our women! We needs wars of annihilation! Dogs and cats living together! Mass hysteria!
7. Interstellar Stakes. Skulking around doing wetwork for megacorps has been coopted by the Shadowrun crowd. This time the PCs have been recruited by the Star League to defend the frontier against Xur and the Ko-Dan armada. Now you must save whole civilizations between commercial breaks.
8. Space monsters and cackling villains. Most foes in Traveller are human or plausible alien sentients with psychologically sound motivations for opposing the party. We need more berserk robots, atomic zombies and Denebian slime devils. And don't forget the Evil Space Overlord and his faceless minions.
9. Hauling freight is for losers. If the PCs end up on a space tramp that fine. But it needs to be a helluva lot more Millenium Falcon style shenanigans and a whole lot less endlessly rolling on the trade charts.
10. Two words: Light Sabres
Discussing "Story vs. Rules" again, are we?
1 hour ago