Obviously, that's not a good thing. It's a pretty glaring internal inconsistency that should have rendered many of Traveller's habitable worlds into nuclear cinders. One way to reduce this inconsistency would be to simply say that velocities are not preserved in jump transit. Just say that when starships drop out of jump space, they adopt the combined velocity of the objects exerting a gravitational pull of them (in roughly the same proportion as these gravitational pulls are felt). Hence, a starship coming out of jump would be a bit like a leaf falling into the water. It would start it's motion based on the currents of the water rather than on any initial velocity it might have had (I know, this is a pretty sketchy analogy, but you get the point).

As for near-c rocks coming in from the outer system, another tweak to the rules that would help a bit would be if there were some way to communicate faster-than-light over short (non-interstellar) distances, so that sensor stations in the outer system could send a warning well ahead of the incoming object. That way planetary defenses could be alerted long enough in advance that they could deploy countermeasures.

Of course, given the very existence of nuclear weapons and the tech-level at which they can be manufactured, this entire discussion is largely moot, as you don't need near-c rocks to destroy the surface of a world. 1950's technology will do just fine.

My apologies in advance if this starts some sort of flame war (as has occurred in the past). I've skimmed the previous debates on this only in passing, never as a participant, so I've probably missed some of the finer details. Regardless, if I'm mistaken in anything I've said above, I'd appreciate being corrected.

I think the upshot of the last discussion was that ultimately it's a lot safer to live inside a small asteroid than it is to live on a planetary surface. Planets, after all, are pretty big targets.