You don't get it, do you, that if you sell a mod, and if in doing this mod, you borrow anything from someone, you will owe him something (unless he is dumb enough to give it to you for free, and you get paid, and him not...).
So if you start selling mods, people won't share with you, because then, the gifters would be the fools, and the sellers rip the benefit of it. This is morally wrong, understand?
So if you start selling mods, it would be the end of the sharing modding community.
I for me don't want that, so yes, I would restrict you in doing so.
Anyway, I'm gonna leave it at that. It's:
A) Not worth arguing about.
B) Not something we can actually change one way or the other, it's entirely in Larian's court what comes of it.
However, seeing the morality of Larian, or the lack of it, I am a little fearfull about this :-(