Commercial food id dry, which promotes kidney disease. Plus the ingredients are crap. Plus, for pet food, there are no truth-in-labeling laws. Your iguana, if it's sub-adult to adult, and is healthy, can easily go for three or four days of not eating. A large fat happy adult can easily skip a week.
This is preferable to feeding fake dry food.
BTW, the smell of the water bowl might have repelled him.