Trump is surely aware of the potential for super-delegate shenanigans. I think he is warning the RNC not to play fast and loose with a selection, and to let the voters decide.
All Trump has to do is ask his lawyer and/or campaign staff, explain how the delegate system works. And if you aren't an expert, no prob...just get me the best authority who does ("and I mean the VERY best").
Furthermore, how well defended are we against dirty tricks by the GOP and our opponents?
Trump is a delegator. You can't build an empire with your own two hands. You have to hire the best and then turn them loose, keeping a watchful eye on their results.
I’m pretty sure the Republicans don’t have super-delegates. The supposed “Democratic” party does. If the Pubs screw the winner it will be with the rule that requires a candidate to win majorities (not just pluralities) in at least 8 states to be automatically included in the floor vote. If nobody does the party gets to decide whose name(s) is/are placed into contention at the convention.