This person got permission for the base. But let me just state that by allowing people to trace your works, you’re opening a can of worms. In my honest opinion, people are going to see that you are allowing traced bases of your works which means to kids “Come, recolor my artwork! I’m a push over!" 

I’ve seen people time and time again allow their work to be turned into traced bases, only to have kids snatch other works of theirs and recolor those works instead of the traced base. Then, being soft hearted, the artist allows it after the kid "apologizes”. 

This bothers me greatly, but I try really hard not to let it even tho I’ve seen this happen time and time again. You really need a sturdy backbone when dealing with kids and protecting your art. 

This is also why I see traced basing as nothing more than recoloring.