I'd just like to say that, as far as I know, CR always stated that resources he uploads to the Hive are free to be edited / shared in any way.
He doesn't consider them "his" art, or something similar.
If I am wrong, my sincere apologies. This is merely what I think to have read on several occcasions.
Note that I'd still prefer to see his permission here.
Edit:
Link to the respective request
Attached proof of CR's approval.