Why not? That is the point. Apparently the reenacting "community" has opened up its collective mind as far as "age" and "size" goes, allowing white males who do not fit those criteria to participate. Apparently it opened up its mind as far as modern creature comforts go (running water, electricity, toilets.)
Gender and race for some reason still seem to have stayed in the 1860s. And women and non-white people are excluded based on some sort of a sad self serving "realism" excuse.
Lee was 54-59 years old in the Civil War, about 5-10 and 170 lbs.
If white males who do not fit those criteria can represent him "realistically", so should non-white, non males.
It is simple: It is make belief. Let anyone be who they want to be. Barney would approve