OIO,
Maybe, just maybe, the P-38 driver shouldn't be expecting to turn fight with Spitfires and Zeros.
The fact that the incredibly generous flap model allows it to do so with the possibility that a sloppy P-38 driver, using his aircraft in a way that it should not be used, may pay a stiff penalty does not change any of this.
If the flaps broke at 251mph you'd still spin. It would make no difference at all to how you fight.