I disagree with the first thing you did. Should've had the boater hook a carabiner to the boat before you roped him in instead of putting another paddler in danger.
Hopefully, no one uses this as a guide for swiftwater rescue. Why would the first paddler approach from upstream and head right for the strainer log? Readily accessible throw bag is in front of the seat, not behind. Hardly anyone carries a non-locking carabiner, but it's probably no consequence.