I've runner faster in my 40s than I did in my 30s and most of my 20s. Having kids shifted my focus away from nights out drinking with my friends to healthier habits. Increased job stress forced me to find an outlet for that stress. Running was it. I think the years of inconsistent training have left me feeling pretty fresh. I'm more than a minute slower for the 5k than I was in college, but I realized the majority of my potential in college and I was well coached.
Take a guy with a ton of talent, who didn't really work at all in his younger years, whose legs are fresh, who doesn't otherwise have tons of choices outside of the fitness world because of past choices, focus his energies in a very specific direction, and I can see a reasonable explanation for his success. Plus, the cumulative miles may be having their positive effect.
Can I make an argument the other way? Sure. But that too would all be based on speculation. I'm just not willing to contribute to taking a man's reputation away on speculation.