He thinks that ideology is good so for him the glasses are ideology, not the cut-through-ideology tool.
But Piper's character didn't have to force himself to put on the glasses. There was no struggle and it didn't hurt.
Using the glasses did cause headaches, but in the real world it's just the same. Once you rebel against bullshit your life becomes very uncomfortable real soon.
But he's deluded. Regardless of his beliefs, the aliens have in fact imposed an illusion (or "ideology" in Zizek jargon) on him, and the glasses do in fact let you see through that (as he himself does later). He can think whatever he wants, but that doesn't change these facts.
"Once you rebel against bullshit your life becomes very uncomfortable real soon."
So, contrary to Zizek's contention, it's not his "enlightenment" that causes problems, but his trying to fight against those with power. A lesser man might have thrown away the glasses after seeing the truth, or perhaps consciously and deliberately started cooperating with the aliens, as various traitor characters did in The Matrix and V, for example.
He has nothing to lose, for everybody else:
I'm more interested in what the movie tells me than in the message the author was trying to convey. If you look at it from the rulers perspective, it will depende on whichever the rulers are. I prefer to look from the perspective of the individual and how propaganda and the need to conform affects my ideas, conscience and behaviour.