i read the eula - there's nothing in it laying any claim to custom map content (referred to as New Materials). the only thing remotely relevant is a little clause about how you can't sell the New Materials:
"you may not"
Q u o t e: (iii) use or allow third parties to use the Editor and the New Materials created thereby for commercial purposes including, but not limited to, distribution of New Materials on a stand-alone basis or packaged with other software or hardware through any and all distribution channels, including, but not limited to, retail sales and on-line electronic distribution without the express written consent of Blizzard;
given that dota 2 is its own plaform and has removed all references to any blizzard IP, it's pretty clear that this doesn't apply.