When I see kids dressed like this, I hope it's them dressing themselves and not their parents forcing them into a look that they feel reflects their own selves. Let children be children! Would he be allowed to play in the dirt in this?
Wow, he looks great. Kids are underestimated. Give them a chance and you will see they know what they like and exactly what they want to wear from a very early age–18 months or so. Let them be themselves and you will be inspired by their self assuredness as much as their own sense of innate style.