I think maybe he means it ceases to be illusory when you realize that it's an illusion.
That still doesn't make sense. Seriously... "That's an illusion!" and *poof* it's now real?
This is gonna be like trying to explain the
fictional character vs
character of fiction distinction.
But first, "real" is ambiguous. There is real vs counterfeit/fake. That's often conflated/confused with real vs imaginary.
A fake dollar bill is not a real dollar bill (using the first distinction), but a fake dollar bill is real (not imaginary).
Using the second sense, a real object is an object, but an imaginary object is not an object. It's the denial that there is an object. It doesn't exist. At all. In any way. No, it's not an actual object snuggled up in the imagination. No object. Not an object at all. The fact we use the word, "object" in the two-worded term "imaginary object" is quite unfortunate and misleading--much like people who hear "abstract object" leads to an awful confusion about the nature of abstract objects--they go off half cocked thinking an assertion has been made that hasn't.
So, real object on the one hand and imaginary (no object at all) on the other.
Tell me, if there is an illusionist performing a trick, is there an illusion? A bit of trickery, slight of hand, misguidance, optical misdirection? There is a show going on, a performance by a performer. You're not imagining it. It's real. What's real?
The fictional character in a storybook isn't going to pop out into the real world, but there are characters of fiction. We can describe goldilocks, rumplestillskin, and our beloved Scooby Doo.
Now to what you wrote. Take out the poof and the now. The counterfeit money (which isn't real) has been real all along--not imaginary. The characters of fiction are as real as the fictional characters aren't. There was an illusion, and it's real, not imaginary.