[GreenLantern]

It would make sense that he was someone they knew before hand because then he could get close to him. In any game surrounding Star Wars right now force sensitives are being revealed by the boat full surrounding the original series timeline.. so it makes sense after the Empire is defeated that more would come forth. Especially if Luke is openly calling to them. So perhaps this guy was older but helped out with the training at the school, then when Ren would ask about his Grandfather Luke would brush it off and not talk to him about it, so he found the information elsewhere. Snoke saw his opening and began manipulating Ren, eventually pushing him to believe that Luke was purposely holding him back or keeping things from him out of jealousy or whatever motivation, causes Ren to snap.