Have they really changed the ToS that much? My understanding was that by EULA the content you create through Warcraft 3 World Editor always belonged to Blizzard and Reforged hasn't really changed much in that aspect.
On the other hand, a lot of custom maps for Warcraft 3 were based on external IPs (Dragonball Z maps etc) so it's not something Blizzard can claim anyway.
Even when transitioning to Dota 2 they had to purge some of the more obvious IP things that existed in Dota 1, such as the sorceress character named "Lina Inverse" became "Lina".