Symbolism, Imagery, Allegory
If this were the 1980s, Sutter would be a Toys 'R Us kid: he just doesn't want to grow up. But surprise: he works in a place that sells grown-up clothes—suits and dress shirts—to young guys getting their first real jobs.
For Sutter, suits represent the way that the adult world completely ruins the innocence and freedom of youth. He even compares the situation to the way modern civilization has crept up on tribal peoples:
Once I saw this documentary about some primitive tribe in the South American rain forest, and they were, like, so cool. They didn't wear anything but these little flaps […] and they walked around in the forest, free and wild. […] Then civilization starts creeping in and the next thing you know, they're wearing these limp T-shirts and long-collared polyester shirts and looking like little winos. It was enough to break your heart. (9.3)
Just by changing their clothes, they've become different people—sadder people. They've lost their native culture, everything that made them who they were. There you go: that's what Sutter is afraid will happen to him when he finally grows up. He's scared won't be himself anymore.
And that's what Sutter hates doing to the young guys shopping for suits, too. He says that these "young dudes" were "teenagers, free and wild" just a second ago … and "now they come into Mr. Leon's wearing their salesman outfits and their bodies still haven't filled out enough to look right on them. They have zits […] from the stress of working their first real jobs and paying their own bills" (9.4).
Growing up actually seems wrong to Sutter, like it ruins a person's natural state. The stress of having to grow up actually causes actual physical damage in the form of zits—not to mention that it just looks physically ridiculous, trying to force a teenager's body into a man's role slash suit.
I Won't Grow Up
Most of all, though, Sutter dreads having to grow up himself: "I know that's the world that's waiting for me out there too," he says. "I already have to put on the slacks, the stiff shirts, and the ties just to work at Mr. Leon's. The real world is coming, chugging straight at me like a bulldozer into the rain forest" (9.5). So for Sutter, adulthood and maturity are destructive forces – something to fight against. Suits represent the stuffy, restrictive world of adulthood – and Sutter wants no part in that whatsoever.
But we have to ask—Sutter seems to see being a teenager as being a carefree, wild kid. But is his life really all that easy? Doesn't he have stresses, routines, and responsibilities that he's just choosing to ignore?