Maybe his word choice was poor. I would say it is "unfair" to expect professional athletes to compete at something without much general recognition and no financial compensation.
Without much opportunity for financial gain, you will mostly get a second tier of professionals willing to go in the hope of raising their brand a bit, since they cant make the races with the highest level of recognition.
The first tier pros are targeting races with bigger recognition (Olympics, world outdoors, major marathons, half marathons, etc) or bigger compensation (large road races) or both (diamond league meets, etc).
Why would a top tier american runner, who needs to run other big races to make their 70k to 150k per year, run a race where they will likely make nothing?
The most likely ways to get top Americans at world cross might be:
1) raise the brand of world xc so high that is has real prestige, so sponsors put bonuses into contracts for placement (just like they do for world major races, world outdoorsOlympics, etc)
2) USATF offer additional prize money to individuals or the team for placement
3) make the prize money deeper at the race itself
Tldr: The bottom line is that pros can only run so many races each year to try to make a living. Adding an important race in March means they have to adjust their schedule and remove another race somewhere else. They'll choose the best combination of prestige and money for their expected level of fitness to maximize their earnings and prestige in the long term. It just isnt their for world xc for the best americans.