AFAIK some athletes may in fact be (somewhat) overweight according to BMI yet still are unlikely to suffer from health problems related to weight gain. An example would be ice hockey players, a large proportion of whom probably have a BMI in the overweight range but who are very fit. A relatively large proportion of their extra mass is muscle compared to non-athletes.

This is probably the minority of athletes, though, so it might be a fringe case rather than something that should be taught as a norm. I also don't know how that relates to COVID.

Terry Crews is 6'2" and 245lbs. That's an obese BMI at 30.6. Does he look obese to you? Fat is heavy, muscle is even heavier, both will cause your BMI to go up. Obviously most people don't look like him so really the BMI figure kind of stops being useful when you have significant muscle.