You're putting way too much value in points at a player development camp that barely resembles real hockey games. Is it possible that it's not payback by USAH? Sure, especially in the Schingoethe case. And with USAH, incompetence is usually a driving factor. But payback is not out of the question and that fact has been admitted by former USAH employees. Chris Peters said "Not ruling it out, but it's been less prevalent in recent years" about the Stranges omission possibly being about payback. A person more well connected than any of us to USAH said that.
But let's go with your points argument. There were 13 forwards that made the Hlinka team and Stranges had more points than 5 of them, and was tied with another 2 of them at 5 points. Since you've only offered points, I'm curious as to how those 7 forwards (54% of the roster) "won spots" and "played themselves on the team" despite not "dominat[ing]?" Or conversely why top camp scorers like Matt MacDonald (2nd), Jonny Meiers (tied for 3rd), Cameron Berg (tied for 4th), Matt DeBoer and Blake Humphrey (tied for 5th) didn't make the cut when they outscored nearly all the players on the Hlinka team? And Meiers, DeBoer, and Humphrey didn't even get into the All-Star game! Or what was Schingoethe doing in the All-Star game and still in the running for the Hlinka team after he didn't register a point in camp? His first 5 pointless games were fine but the 6th was a bridge too far? You ask that I "see why USA didn't pick them" based on points, yet one of them outscored/tied in scoring a majority of the Hlinka forwards and the other made it to the All-Star game despite not registering a point? That petition request in USAH's favor doesn't comport with the actual camp results.
It's good that guys can make the team based on great camp performances. That's the way it should be! But guys should also be evaluated, and possibly make the team, based on the totality of their performances and abilities, even if they have poor statistical camps like Schingoethe. If a guy like MacDonald statistically dominating the camp isn't enough to take him from off-the-radar to on the Hlinka team, why should 6 games of unstructured hockey override what Schingoethe did in 62 games in the USHL last year to take him off the team?
I'm not even a big "USAH holds grudges" guy. I think nearly every time someone claims USAH has an axe to grind against a player - think countless CHL cuts / snubs at the WJC - it's not a grudge but incompetence or player preference. I think that's the far more likely explanation for Schingoethe, even if the cut is still largely indefensible. But USAH has clearly demonstrated an axe to grind against players that sign with the NTDP and then bolt without honoring the contract. It's been well documented and admitted by those-in-the-know. And if USAH would leave off Stranges, a player that independent evaluators say would be the most talented, best NHL prospect, and best player on this team, for any reason other than retribution than they need to rethink their entire approach to the Hlinka, player development, and player selection, because that type of incompetence would be shocking.