I'd have to agree with this on the level of likely media awareness of a young child... if you're looking for heroes he won't have to explain, then these are probably the most scientific... not rigorous in the sense of a University Physics lab, but a heck of a lot more rigorous than most anything else that gets wide media attention... identify what to test (myth), give initial hypothesis (explanation), identify how to test, revise if necessary, test, scale up, come to conclusion, revise in later shows, re-test, etc.
Other "heroes" to consider might be internet entrepreneurs, who while not being scientific themselves, managed to take new technology in directions not grasped before... Facebook, Google, Netscape... might be more commercially oriented than you want, but still, it's an area your son and his friends will know well soon, if he doesn't already.
Unfortunately true scientific or mathematical skill comes with a lot of background work and most don't get the credit they deserve, even when older, but definitely not while they're still learning.
I told my daughter (now 17) that true skill takes time, and the flashiness of athletes and movie stars almost always dies quickly... a few make it, but thousands don't. I tried to teach her (I hope successfully, and her math and science grades suggest I might have succeeded at least a little bit...) that a hero is one who sticks to her guns, as long as the evidence supports her, and isn't afraid to admit when they were wrong and change their theories. The hero is one true to the search, not the result... cause it only takes one bad result to take you down.
Hope this helps in some small way :-)
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I drank what?