If there were directly a settlement transaction attached to the output of the funding transaction, either party could always close with the initial state after the 10 blocks have passed since the funding transaction must be confirmed on the blockchain for a channel to become operational.

From what I understand, the first settlement transaction attaches not directly to the funding transaction, but to the first update transaction. Then, the funding transaction be safely published to the network to establish the channel, and the CSV only starts counting down whenever the channel closure is triggered by publishing one of the update transactions.