The only thing validating the choice is a still-hot production line with all the tooling and logistics in place. If they capitalize on that correctly, they will get the speed and costs they seek. Otherwise, as Francine noted elsewhere on this subject, "If not, we're totally screwed." I completely agree.
https://members.boardhost.com/Warship/msg/1766696868.html 
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I think this may validate the choice of the Legend class design for the future frigate class.