I gather it's not directly related to the trio there, but just the underlying assumptions showing through. These people represent the slave traders of old, or the people who enslaved animals for food, or whatever pushes Riker's buttons.
Picard seldom lets such things show, is all. His utter disgust at the revelation of the true motivations of the "terrorists" in "Starship Mine" is one of those occasions. The cultural canon might still be the same: there's no point in speculating that a German who lived in the 1930s-40s might not have been a Nazi, or, for a milder example, that a Yankee from the 1870s might not have been a carpetbagger of the worst sort, and you should always suspect the worst and only then, if events really warrant, choose to exercise the benefit of doubt. It's the more natural way to do it, the farther in the history the disdainful way of life is. After all, the crime is the more alien then as well.
Of course, Picard is also the man with perspective, capable of seeing that each era has its own woes. Even if he cannot see the wrongs of his own time, he won't be deluding himself into thinking there are none. This, though, is no reason not to condemn those wrongs that mankind has already left behind.
...Now, if we just could find such a decidedly left-behind wrong in the reality of our own world...
Timo Saloniemi
