I was a CS major / D1 athlete and I'd have to say it's not entirely unrealistic -- while there is the dumb jock stereotype, a lot of college athletes have a pretty good work ethic due to a good training ethic. Though some end up with just a party ethic
Just before my senior year, I was able to help co-found a startup as well (which is now 4 years running), while competing at a national level
But yes, there were only 4 or 5 engineers among ~50 guys. I think it's more that a lot of the people who lean towards engineering in high school are usually not the athletic type -- though I suppose this article is more about the athletic types interested in engineering