IIRC although working from memory which could be dodgy the Alabama was in fairly poor condition after being at sea and without proper refit or repair for some time. Checking wiki see
CSS Alabama final cruise, that seems to support this as Captain Semmes of the Alabama wanted to "
dry dock and overhaul his ship, much needed after so long a time at sea and so many naval actions" With the arrival of the Kearsarge very shortly afterwards and "Having no desire to see his worn-out ship rot away at a French dock while quarantined by Union warships" Semmes decided to fight and issued the challenge. However the poor condition of the Alabama's powder and fuses and superior firing of the Kearsarge made it a substantial mismatch.
I suspect that given the better condition of the blockading ship running would have not been a practical option. It was either fight at longish odds or rot away in the French dock.
Steve