Quite.
But unless you could quote the speeds relevant to the flap selection and stall speeds, and the acceleration/heightloss relationship, there is no point suggesting it was anything other than an inspired guess.
In fact, it worked, so it all worked out OK, but let's not pretend there was an evaluation of the aerodynamic factors involved in any detail. What if the sink associated with the flap retraction had caused an earlier contact with terra firma? You would all be criticisizing such a subjective and wrong decision.
He guessed.
He guessed right.
He'll make a fortune from the Clifford Industry.