In a fixed sized population each instance of a neutral mutation will be passed on to one offspring on average. I'm pretty sure this is what Dan meant. It is intuitively obvious to me. If you reflect on it I bet you will get it. If not I can explain.
"In a fixed sized population each instance of a neutral mutation will be passed on to one offspring on average. I'm pretty sure this is what Dan meant. It is intuitively obvious to me. If you reflect on it I bet you will get it. If not I can explain." You do realize that even what you say above is not a 100% mathematical expected success rate, don't you?
Dan said 100%. That's his claim. He's added later qualifiers to his claim in an attempt to distance himself from that position, but no matter how much spinning or word-smithing is done, you still don't expect 100% of all mutations (neutral or not) to be successfully passed to subsequent generations.