Of course full nodes that don't mine will never get a block.  'Good' non-mining full nodes could enforce the rules, though, but only if it somehow happens that at least one 'good' node is between every conspiring 'evil' mining node so they would not be able to propigate blocks to eachother. Last I saw (which was a while ago), the large pools have a special semi-private "relay network" for their mining full nodes they use, and they could always directly connect to eachother. Users that actually want to get their transaction into a block (since non-mining full nodes don't make blocks) would have to connect to an evil node. There's also nothing stopping the 'evil' guys from popping 100 000 non-mining evil nodes on the network to make it easier for users to connect to the evil-net.