It is the end part of males's seasons. But Relocation Stress can last for months.
Almost 100% of igs are strongly bonded to their enclosures. When you reach in, you are violating territorial instincts that they carry genetically. Many get over it, and many don't. But in the habitat, when the towel covers his eyes, he stops acting out because he can't see anything. I think that is the kindest way to get hold of a skittish, threatening and frightened iguana.
Then press him against your belly, and go sit on a chair or sofa. Unfold the towel until you uncover his head, and just wait there, talking to him. It would be great if he accepts treats like banana, grapes or bits of pizza crust. Be ready for him to lunge for freedom. Again, never let that trick succeed.
I'm going to start advising that people who are training their igs, or who have scared, skittish igs, to never look directly at their faces. The direct, eyes-forward stare is the look of a predator that is known to agitate stressed iguanas. He stares at you to see if you are going to stare at him.