Do you care to cite those conflicts? Are 18th century reformers beyond a mote of cynicism? That sentence isn't claiming to describe the entire world view of the reformers, but to specifically note that they would have been aware of the number of examples where the masses were not deterred by the spectacle of executions. (You seem to take offense with specificity in a claim?)

It is possible to declare the system of executions a travesty, while also observing that the lower classes are willing to phsyically intervene in them. Perhaps it is even possible that the reformers were made aware of the injustices by the lack of respect the lower classes demonstrated for them.

Perhaps a reformer with the goal of abolishing executions would pen a treatise that was justified in the moral terms of the ruling class, rather than based on the emotional state of the working class. One would look to address your audience after all. I'm not familiar with the cited reformers you claim are conflicting but it sounds more like aristocracy convincing aristocracy, rather than an aristocrat attempting to sway the masses with pamphlets.

I question whether you read this text in good faith, or are simply searching for bits you can pick out to summarize on a message board and construe as contradictions.