Geoffrey Mutai 5'7" 119 lbs
Wilson Kipsang 6'0" 137 lbs
Patrick Makau 5'7" 121 lbs
Paul Tergat 6'0" 137 lbs
It seems like these guys are all leaner than your formula predicts. You could continue on with this list. And if your formula were to hold true, a 2:04:00 guy would need to run even faster over 200 meters, and would thus require more mass to do so.
The idea that if Hall were 6'0" and 142, his muscle mass would only support ~2:07:40...that's simply not provably true. With all due respect, I think you're getting too wrapped up in your numbers.
Although some of those guys are probably slightly shorter than what you listed like Tergat at 5'11.5", you are right they are lighter than the formula predicts. You'll note that those you listed as well as those you can add to the list will primarily be East African. It's not atypical for East Africans to have legs that are slightly, but still statistically significant, longer than most populations. Those you listed were likely below 5% bodyfat at race weight too, most certainly Tergat who looks like a completely different man nowadays.
The rare European-descent guys you can add to the list, like Ritz, tend to have careers riddled with injury problems. Too much stress on the connective and structural tissues relative to the muscle IMO.
To be sure, I'm not getting caught up in the numbers, they are just a guideline. If the performance is where you want it to be and the health/longevity is there, then don't change a thing! Same for someone like Priscah Jeptoo, who's form has come under much scrutiny. Who cares about her form being "bad" if she's crushing it and is healthy, don't change a thing!
Again, it's just a guideline or resource to consider. For those who have hit plateaus, aren't running well, having injury problems, etc. they can take a step back and see if they have less mass than it normally takes to run a certain time, or if they have more than the required mass it typically takes to run a certain time (a la Nick Symmonds). If they fall outside the hi/low range they could consider the option of changing their body composition if their diet, training, sleep, etc. has otherwise been very good and consistent for sometime.