|Romney Had His Cross-hairs On The Big Yellow Target|
You'll hear all of that from the GOP establishment and the #NeverTrump movement.
It is worth keeping in mind that the pro-establishment voices (and The Omnivore will count movement-Conservative bloggers in here as well, even if it's an alliance of convenience) have faced a reverse of the current situation before and had a, shall we say, different reaction?
In the run-up to the 2012 election candidate Ron Paul was orchestrating a delegate operation similar to what Ted Cruz is doing--but even more underground. He wasn't getting officially-friendly Paulites onto the delegate slates--no. He was telling his supporters to dress in suits, cover up their tattoos, and hang out and try to pass for normal after caucuses and what-not to try to make it into the delegate selection process as submarine Paul-voters.
THEN, in the event that Romney came up short, it'd be the Ron Paul show. No one really knows how successful this was--but there was quite some consternation.
Enough so that Ron Paul was essentially disallowed a (toothless) nomination on the floor of the convention by, essentially, establishment fiat. This was a fairly blatant shut-down of a grass-roots candidate who was out-playing the Rominee at the delegate game. The Omnivore will note that Ron Paul's strategy, while well executed, wasn't nearly enough: Romney easily had enough to win on the first ballot.
However, that wasn't enough for the GOP. Hoping to prevent such an insurgent again, they instituted the infamous Rule 40(b) which was designed specifically to stop a 2nd coming of Ron Paul (or similar). This rule, which required that potential candidates win a majority of delegates in at least 8 states to be considered, would exclude insurgents who could get a plurality of delegates but consistently fall short of a majority.
Donald Trump was the first candidate to meet that bar in the 2016 GOP Primary.
Rule 40(b) will probably be the first thing thrown out at the RNC rules convention: it backfired.
The point here is that whatever you hear from blogs, the RNC, or other commentators you did not hear it back in 2012 when the shoe was on the other foot. When Ron Paul was outplaying the favored candidates there wasn't this rules-are-rules attitude towards his ground-game.
The concept of fairness is a tricky thing. The Omnivore fully supports the idea that a party ought to be able to choose its strongest candidate--or--at least, create rules that account for post-primary strength (which Democrat super-delegates do). It is also clear that The Party exists to serve more than just the slice of primary voters: A party can, in fact, stand for things ('stand for things') even if the rank-and-file doesn't vote in every primary election. Donald Trump, by and large, doesn't fit the model of a conservative candidate.
A Note On Fairness
On the other hand, Donald Trump does fit the stereotype of a Republican candidate. His racist dog-whistles, bombastic foreign-policy tough-talk, and border extremism are all the caricature of the GOP that the establishment has denied for, well, a couple of decades at least. It just turns out that stereotype is a winner, electorally speaking.
One constant complaint of thoughtful conservatives has been that the right-wing media has sold its (credulous) listeners on a variety of ideas that are just not true (like the idea that Barack Obama is a catastrophically unpopular president and anyone running against him will have an easy time of it). What they are ignoring is that they, too, have sold the GOP voters on the idea that the the Republican party is their party--that the ideas like super-immigration restriction (such as a wall and 11MM deportations) are within bounds for the party platform.
They have also pretended that, for example, Romney was a legitimate candidate because he won the primary--his nomination was the will of the people. That was true--but it was equally true that Romney, despite his protestations, represented an idea of what mainstream America wanted the Republicans to be like rather than what a pretty significant faction of them actually were. Romney as a moderate, wealthy Republican, was a caricature of a compassionate conservative. The intense back-lash that we saw after his defeat was evidence that the GOP didn't really want that.
So what's fair? That's the wrong question. The question in politics is "What can you get away with?"--but just be aware that whatever you can get away with--when it goes your way? That's what you're going to call 'fair.'