Just to be clear, only the first max_cluster_size - 1 participants will be able to spend their outputs in separate transactions before the parent transaction is confirmed, but yes that is correct.
Note that today, the descendant count limit (25 transactions by default) already imposes a restriction on unconfirmed spends of outputs from a single transaction. While we haven’t finalized a proposed cluster size limit yet, my hope is that we’ll be able to support a number that is bigger than 25 (in my draft PR, this number is set to 100 for now).