As I said in a different thread, if a person puts down no defences, they should get ZERO rewards.
Why click the join button, only to not bother taking part and waste other players time and effort, especially if they then attack (which has happened to me)
How about as a sort of consolation prize, for a total clear of all the opponents territories, you get a 500k prize.
So those people who face a no-show opponent will at least get something from the wasted time and effort