Regarding the conviction of a secular person for an offense

You can say anything. Is there a prohibition against causing a minor to stumble in a transgression? He is not halachically obligated. Several poskim have written that spiritual harm is caused only if there is a transgression in the act (mainly with regard to breastfeeding a baby and going by the Ketubot S and Shulchan Arba on breastfeeding a gentile). In any case, it depends on the question of whether the prohibition of stumbling is due to the spiritual harm. It is certainly possible that even if there is spiritual harm, then there is a point not to stumbling, but still this does not mean that there is no blind eye here. Think about a single Ivra Danhara. Looking at the harm, I would always expect there to be a prohibition in this, as in the case of the Ivra Danhara (although my fault is less, but I still create harm in the world with my own hands). And the same is true with regard to making him wicked and dying, looking at the harm, there is never any room to distinguish between wicked and righteous.