I'm broadly sympathetic to your point that Aaronson's algorithm is measuring something like conformity or group consensuses rather than morality, but the specific example you picked to garnish that point is dodgy. From Randall Collins's Violence: A Micro-sociological Theory, pages 425-426:

But in fact, as I have tried to show throughout, violent confrontations generate their own situational emotions, above all ten- sion and fear; and we see this on the faces and in the body language of most of the crowd during these events. The demonstrative extremists are not expressing an emotion that we can safely infer, on the basis of the evidence, as generally existing in the crowd; they are another specialized minority (different as well from the minority of violent activists) who have found their own emotional niche in the context of the crowd. And in fact the bulk of the crowd does not usually follow them, even when it is safe to do so because there is no opponent present but only a dead body or a captured building; the demonstrative extremists are usually separate from the rest of the crowd.

Some evidence bearing on this point comes from photos of lynchings in the American South and West in the period 1870-1935 (Allen 2000). Most of these photos—and the ones that are most revealing on this point—were taken several hours in the aftermath of the actual violence, or the following day. Individuals offering acts of gratuitous insult to dead bodies are safely disconnected from the actual commission of the violence. In a photo (Allen 2000: plate 93, not shown here) we see two white men standing beside the body of a black man hung from a tree, one poking the body with a stick, the other punching it. In the background are four other white men looking on. In another photo (Allen 2000: plate 25, not shown) a young man leans nonchalantly with his eyes closed against the post from which the charred body of a black man, lynched the previous night, is hanging; the nineteen other faces visible in the crowd are somber. This is the usual pattern in all the photos: a few are the demonstrative extremists; most of the others are somber, serious, awed, or uncomfort- able in the presence of death. [I skip a paragraph here.]

But the mood of demonstrative extremists in the aftermath contrasts with the emotions that are displayed during the actual lynching itself. In a rare set of photos, we see a lynching while it is going on: a black man showing the welts of whipping on his back stands in a wagon shortly before he is hung; his executioners stare at his face with hard, hostile stares (Allen 2000: plates 42 and 43; not shown here). There is no clown- ing, no expression of joy; these are the frontline activist few, engaged in an angry, domineering stare-down. A violent confrontation itself is tense; even when one side has the upper hand (the usual formula for successful violence) it is compelling, focused into the business at hand, unable to ironicize it.

Thus the demonstrative extremists, operating safely in the aftermath, show something else: an attempt to raise themselves from the bulk of the crowd, the back line of merely nominal supporters of the violence, and to raise their status by closer connection with the violent action that had galvanized the attention of the group. By putting themselves close to the dead body, engaging in gratuitous acts of insult upon it, they put them- selves closer to the center of the attention space.⁹ The most blatant expres- sion of joy among Allen's (2000) lynching photos is in plate 97 (not shown), which shows two well-dressed young men grinning (rather mirth- lessly) at the camera while viewing a black body being burned. This was not in the heat of the action, however, but in the aftermath; the victim, accused of molesting a white girl, had already been hung from a lamppost and riddled with bullets. These cheery demonstrative extremists are prob- ably proud of themselves for standing so close to the workman in grimy overalls who is tending the fire; everyone else in the photo is farther away, and the twenty-nine other visible faces range from somber to apprehen- sive.

The last photo Collins refers to ("plate 97") sounds like it's your photo 2, and Collins's interpretation of it seems to me to fit better than the one you imply. I wouldn't go as far as to say that all of the "twenty-nine other visible faces range from somber to apprehensive", as a few of the people in the photo are evidently just trying to get a closer look, and a boy near the front seems more intrigued than anything else. Nonetheless, the crowd as a whole doesn't appear joyful or celebratory to me.

Turning to photo 1, I see perhaps ten spectators' faces clearly enough to make a guess at what they're expressing. Going from left to right, I see (1) thick-eyebrowed man in cap in background who looks as if he's whistling while thinking hard about something; (2) foreground man in white shirt with no tie with neutral-ish expression, but maybe happy; (3) man in middle distance with shorter man in front and a boater-wearer behind, the former gazing off to the photographer's right with a worried/pensive look; (4) smirking man in tie; (5) foreground woman in dress with irregular spots who looks surprised/wary; (6) another woman behind her with open mouth, who might be amused or surprised or scandalized; (7) cluster of three foreground women, where the nearest one's face is too blurry for me to interpret, but the two further back both look apprehensive; (8) foreground man with moustache, pointing as he stares intently; and (9) man at right edge with left eye not visible in photo, looking not especially happily to the photographer's right. As in photo 2, although there are happy-looking people present, they are a minority.

I don't believe it's accurate to use these scenes as examples of rightful celebration or joy. fubarobfusco's warning to exercise caution in how we read these photos may be well-advised.