I agree, he does not seem to have quite the same tones as the rest of the group, and there is no evidence of him between the arms of the young women he is "standing behind".
The date suggested, some time in the 1880s, seems right to me, too.... is there any suitable death for him near that time? The only other times I've seen people "pasted in" is when a deceased relative has been included in a family group by that means. That might assist you to fix a close date.