On one hand, I think Oda is setting Shamrock up to be a different sort of Celestial Dragon with his own dreams and goals. I mean, he even showed a weird amount of respect to Loki.
On the other hand, Shamrock DID orchestrate the kidnapping of the giant children and attempted destruction of Giant history

>>281990387
Sommers still looks young, just slightly older.
Either he's been given eternal youth like Gunko or he's aged much more gracefully than Garling did