Jeez have you never heard of being a gracious winner?
I think his remarks showed the same kind of class he showed when he waited with Ben Carson. The other guy is in a difficult situation and you give him a bit of cover. Now that Jeb! is gone I'll give him a fig leaf to hide his naked incompetence too!
It's also about building bridges to folks who supported Jeb! and to the party people so they understand that after the fire fight he is going to be someone that will be dogged in the process of getting where he has committed to being (A Wall, Immigration Reform, Strong Military, Trade Deals that benefit the US, No Obamacare-free market system w/ saftey net, care for Vets etc) but that he will not go scorched earth on them as long as they come along.