Anyway for young children, I would imagine that an entry level like the Canon 450D/500D or 1000D/1100D, Nikon D3200 or D3100, Pentax Kr/ Pentax K-30, Sony A37, etc, will do really well. This is because you would not want to overwhelm your boy with too much controls and dials, although children tends to adapt and learn very fast, but too many switches, dials and stuff might still be a bit intimidating.
I would like to say that since you are using Canon and would imagine that you do have some lenses in your arsenal, so the cheapest way to get things started is to stick with the Canon, that way, your boy can use your lens and so it would be easier on your wallet.
Anyway, you have mentioned that your boy did not like using liveview, but actually there are some mirrorless out there that have electronic viewfinder which more or less look and feel like a normal viewfinder of DSLR. To name some of the cameras - Olympus OM-D, Panasonic GH3, Samsung NX10/ NX20, the GH3 and NX10 look and feel abit like a smallish DSLR while the OM-D feel like a small rangefinder style camera which took on some heritage look and feel from the old Olympus OM camera.
If I was to choose, I would definitely give my boy a cam body that I am familiar with and had large arsenal of lenses... in my case - Canon and Olympus. And for your case, I would imagine the camera brands to be Canon and Samsung (namely, Canon 450D/ 500D or if you have money to spend, then get him the latest 650D. or Samsung NX10/20.)