Silverfish knew he had a clear advantage over Jian in that very moment. Not only did he have informations about, but the boy was in his camp completely defenseless and without any weapons. If that wasn't enough already, the story of the fallen dragon had drawn the boy's interest.
However he seemed to have a clear idea of what he wanted to do with that dragon, and that's surprised Silverfish. The grey-haired boy only wanted to go there because the Flies wanted something from the dragon, but he was well aware of just how useless a dragon corpse was. The scales were insanely hard to get and nearly impossible for most people. Same for the teeth, or really any parts of those flying lezards.
Plus, dragons were animals not spiritual beasts. As such they didn't have the core that cultivators could draw Qi from. Not that Dragons could even use Qi, that would be terrific.