Greatest U.S. Olympian

He's right in a sense. Most of the swimmers compete in more than one discipline from the earliest levels and there is a lot of crossover between strokes and distances. On the other hand, no runner is or will ever be world class in both the sprints and distances, and only a few cross over from track to field (and those who do often wind up as decathletes or heptathletes). You'll see world class long jumper/sprinters, but nowhere near as many as swimmers who cross between strokes, and guys like Lewis and Owens who are medal-caliber in both are extremely rare.

There are far more medal chances for an elite swimmer than for an elite track athlete. Same with gymnasts, with the team, all-around and individual apparatus competitions.

Edit: Oh, yeah, and there are more relays in swimming than track, with far more crossover. There are very few runners good enough in both the 4x100 and the 4x400 to make both teams at the world championship/Olympic level (Allyson Felix comes to mind, but they are rare).

 

Oh please, Dr. Spock > Mr. Spock

 

Surely there has to be some Olympic event where that sleeper hold thing he does would let him dominate. Wrestling? Judo, maybe?