How old is your boy? I agree the Amos Rd trails have some solid climbs and technical descents. Great riding, but not a beginner area. In fact I think the biggest problem with most trails rated green has little to do with how good you have to be to ride them. Rather it's about width, exposure and height of obstacles. Makes little sense to me and I've built a fair bit of trail.
If you go to a ski area as a beginner and ski the green trails you may find a fair bit of challenge, but you won't have to go to another place to ski easy trails. It's too common in mountain biking and explained away as a right of passage too often. I've seen an awful lot of riders out of their depth over the years of walking and working on trail maintenance. Sometimes it's their (also read my) fault, but mostly it happens to people who would not have even gone riding if they knew what they were in for - trail so different to any path they rode before they just don't cope. We need your boy as well as girls and young women and old women and everyone else to ride MTB because the more we have riding, the more will work on trail and the more leverage we have on land managers to expand their MTB systems.
Would your boy like to try the ride dirt track from Main Beach to the Seaway on the Gold Coast? It's pretty flat, but sandy and a bit wind exposed, but feels like a real ride and there's a cafe near the seawall carpark. Also a big grass area in the park at the end of the spit to cut through to the Broadwater side.