Wouldn't this technically break the BB license?
As you point out, the license says you can't use the BB body (modified) as the basis for a new race. This is not the intention - the whole point of this is that it can and should be used with the BB original ESP. This will be an upgrade that uses BB,
not a replacement for it. Only meshes/textures will be provided, you'd still need to get and use the original BB mod and then copy these meshes/textures over the top of it when installed.
However, there are additional "variation" options that could be provided by adding slight race variations through ESP. It's questionable whether you would be breaking the
spirit of that license by adding a "redguard with tattoo" race or "fat dunmer" race or "old Imperial" race based on a variation in UV or shape (with or without a different texture), applied to a few individual NPCs. After all, there are "Better Bodies versions" of the Tribunal gods etc. and those don't seem to be an issue... :shrug: