Let's say he has N friends who have agreed to help. He doesn't want to allow any single individual to have the power to act alone and release information. And, he doesn't want to require all N of them to act together. What if one dies, is arrested, etc.? Could he encrypt the documents with, say, all combinations of three friends' own public keys such that a quorum of three friends would have to cooperate in the release? He would end up publishing N choose 3 bundles.