Play it then?
Any character that is a Luffy main fight will have greater relevance then any character that isn't a Luffy main fight. Literal exact thing happened with Kaido and BM in Wano. We've seen many people from Gaban to Kizaru mention Kaido after he got defeated, but nobody cares about BM's defeat. Shanks/BB didn't even care when they took out Law and Kid.
Shamrock is the captain (top) of the GK's. GK's is likely the main opposing faction of Elbaf and therefore its likely that the captain of the GK will matchup with the captain of the SHP. Since his a Luffy fight he'll be the peak of the gods knights and have extra relevance, unlike Garling whose obviously just there to somebody of note against Dragon. Luffy isn't fighting any of the Gorosei again, and the arc he fights in will be focused on Imu, so he'll be irrelevant except to his and Dragon's fans, (like King/Queen in Wani), mean whilst since Elbaf is shaping up to be the GK's arc, Shamrock, the current captain will get a whole arc dedicated to him and centred around him, like Kaido was centred around in Wano.