If that's not an exact answer, what is?
An exact answer would be one that isn't circular.
SCJ was asked why the scientific method doesn't apply to God. His response: because it doesn't apply to God.
I am no more informed after this answer than I was before it. A real answer would attempt to give some reasoning or validation as to why.
If I say that you can't use a spanner to undo a screw, and little Jimmy asks why, it's not an answer if I tell him that spanners don't undo screws. It's practical advice, in a way, but little Jimmy doesn't understand any more afterwards than he did before.
A real answer would be to explain how a spanner can't grip a screw in the right way that you need in order to be able to undo it. A screw needs to be undone with a screwdriver, and a spanner isn't the right shape. If I wanted to be really detailed I could go into how the forces are applied and so on, but most people would probably get it just from the above.
From that, Jimmy could learn that actually the shape of the tools are important. He can probably extend that to figure out what things you can and can't use a spanner, or a screwdriver on.
It's a lot harder with science and religion, because the scientific method is designed to be as generic a tool as possible. It should adapt to learning about absolutely anything. Religion or God, on the other hand, is not easily described. It's not like a screw, where it's easy to say that you need something wide and flat to put in the slot. It's difficult to describe exactly how one learns about religion, and this is where most people (including SCJ) fall down. They can't describe it, so they don't. They attempt to handwave their way through it, because that's what they found acceptable.
That's not good enough.
If you want to make statements like science cannot be used on religion or God, then you need to be able to explain why in very specific terms. "Because I said so" is not good enough.
If only one viewpoint is accepted as valid, there's not going to be much discussion, is there?
But if your viewpoint is unintelligible to others, you're doing an awful job of explaining it, and there's not going to be much discussion either.
If you deliberately format your answer so that it's circular reasoning, you probably shouldn't be surprised when people throw it out as gibberish.
The next question should be: 'Why is it not within reach of the scientific method?'
Well, most of us would consider that to be implied by the first question, but if you really want to separate it out...
Is that not the essence of faith?
So the simple answer is that it's not reality, everyone makes up their own mind? You can't use science because there's nothing there to use science on, it's only what you choose to believe?
Given most of the rest of what SCJ said, I doubt that's his (or your) answer. Christians believe that God is an objective reality. He does not simply exist in the imagination of believers, or he couldn't have created an entire universe.
The truth is that it's a have-your-cake-and-eat-it-too sort of thing. Christians want to believe that God has had, and continues to have a real effect on the world as we know it, but also want God to be ineffable and undetectable.
You can't have it both ways, I'm afraid. Either God interacts with the universe that humans inhabit (in the form of creation, miracles, communication with his believers, and so on) in which case he's detectable. Or he doesn't, and we shouldn't care whether or not he exists at all because He has as much impact on humanity as Russell's Teapot.