It's pretty much the porn ruling. I know what is an appropriate plan is when I see it.
I mean, each kid needs their own plan. What's challenging for one kid won't be challenging for the other. In this case, Gorsuch and the lower courts used a case for precedent that was about a girl who had impaired hearing and wanted someone to sign during all of her classes in addition to having an extra loud speaker setup that the school already provided. In that case, the girl was doing better than the rest of the class even without having someone sign all of the lessons. The court decided that the school didn't need to do more than they were doing and the idea that a disabled child deserves an "equal" education isn't fair or necessarily possible.
Obviously, that case is not relevant in this one, since autism is a completely different disability and the child was not doing well with the IEPs that the school devised and never bothered to change. They were treating IEPs like a formality and rubber stamping them and the parents balked. They took the kid to a special private school where he did much better, and then they sued the school to have them pay for the private school tuition because they clearly weren't doing their job in providing an adequate education.
The lower courts said, nope, as long as the minimum is done, it's fine. The Supreme Court said, nope, minimum isn't good enough, you need to make sure the IEP is actually individualized and since the kid did improve at the private school, it shows that the public school IEP was lacking.
And that you can't standardize this stuff. Kids are different, disabilities are different, but IDEA states that kids should get more of an education than just "de minimis."