It's ok as long as Trump selects the delegates his votes earn him. If Trump selects someone who changes his/her mind, that's one thing. If Trump wins an election, and the RNC puts in an RNC stooge to be a Trump delegate, that's another.
In many states, the candidates don't select the delegates - the state party does.
The RNC doesn’t get to cherry pick delegates. The state parties get to decide how their delegates will be selected. It varies by state. You do believe in “state rights” don’t you?