In many states, the candidates don't select the delegates - the state party does.
I’m aware that some states have different rules for how delegates are selected. And I am still saying it is not ok for the state party or the national party to select delegates FOR a candidate. The delegates won by a candidate should be people who are actually supporters of that candidate. The delegates do more than pick the nominee. They vote on the party platform, for example. The delegates at the national convention should reflect the voters who voted in the party primary. Otherwise, the RNC is just wasting our time.