He puts Cabbage in charge of protecting Law and Robin
And it was done in an rushed way with no emotion, like he was taking care of a checklist. You'd think a scene where the things that restrained Yamato freedom for 20 years are destroyerd would have more gravitas to it
He laughed with Shirahoshi when he still disliked her. Chapter 614
Nothing makes Yamato more than a strong arc allly
Cabbage became number 1 of his fleet.
It was calm, showing the mastery and ease with which he could do it...
Shirahoshi will be important in the future war. He "dislikes" crybabies but still allies and supports them.
Yamato is strong enough to be helpful to Luffy and has a promise from his dead brother to be on his ship, and has a direct awareness and respect for his "hidden" dream. You want her to stay on the island she was trapped for 20 years, among citizens that fear and despise her soon to be exiled father, when she wants to sail the seas and be free. Don't get me wrong, it's possible, but saying the alternative isn't also fairly possible too is strange.