User blog comment:LEGOSuperDKong/New rules for CUUSOO (and the end of many popular projects)/@comment-5955017-20131212220413/@comment-5671588-20131213190855

They did explain that more thoroughly in their blog; royalty was received for the original Minecraft project but not for the other sets as they did not come directly from the CUUSOO project but were products of Mojang and LEGO's new collaboration.

I think that it is good that they clarified this; it was strongly implied that they would not accept theme propositions beforehand but was never fully stated in the rules.