Good Trump tactic. Try to make the entire delegate process the nexus of evil just because they are doing what they are supposed to do and he can't get them to do his will and just hand the entire thing to him.
Obama did a similar thing in 2008, but he was much better at upsetting the applecart.
I wouldn't say the delegate process is the "nexus of evil," but in many states (maybe all, or some, whatever), there is a delegate fee in the neighborhood of a thousand bucks. That alone is prohibitive for a lot of people. And as for "doing what they are supposed to do," are they supposed to freeze out people who haven't been glad-handing and schmoozing for years? And then file it under, "well, they just didn't understand the process..."
BS. I imagine the rules vary by state, but where I live, you must A) have been a Republican for the past whatever length of time, B) inform the county chair of your intention to run for delegate, C) show up at the county caucus, give a stump speech. So what can they mean by "not understanding the process?" In the minds of a lot of these big-time small-town horse traders, the most integral part of "the process" is being in the club to begin with, and they don't get why the rest of us don't understand that.
And I would stress that I'm not saying they're bad people necessarily, but it's human nature. There's always these people, on the committee at the range, in the hunting club, who just care way too much about what they perceive as the prestige, the weight, of being in a higher position in their hobby of choice. And after they've been the big fish in the pond for a while and come to view the process as their very own, they get ticked when nobodies try to horn in. There are others who do a lot of work for the party locally, and view delegate slots as their rightful reward...But THAT is not how the process is supposed to work.