The hole project is divided in 6 steam accounts. The guys that made this mess formated their PCs, and the original map files don't exist anymore (can't republish through Portal 2 app).
Considering we have many accounts in the project, supose that account "A" made the collection, but the "for friends only" maps were made by acconut "B". The "for frieds only" B's maps can't be published in an A's public collection even though A and B are steam friends, and A subscribed B's maps...