A pilot in the 115-125lb range which is quite easy for some of our shorter women would have a very hard time doing the high strength, high reps, cardio training necessary for the M1 and other G-runt maneuvers designed to clench neck, trunk and thigh muscles to keep blood in the upper torso.
Since the seat slams you hard enough, even without the woolie cushion that most pilots use, to make 3 ejections (for a 160lb, weight trained, male) a fighter flight qualification ender, the weight of flight gear means likely nothing because body mass is an indication of muscle and bone density to which kit adds nothing but more topical bruising to if you ever have to leave the jet in a hurry.
Bluntly, a small woman could come out of this crippled or with chronic health issues and nobody will do anything about it because...diversity is more important than economic or capability driven metrics.
One does wonder how they managed to reach this astonishing bit of obviousness, given that instrumented dummies have likely been riding the rails since the mid-90s (the Mk.16 is also on the Eurofighter and Rafale for instance).
What is more ominous is that the F-35B, like the Yak-38, has an automatic mode to clear the pilot without any chance to 'assume the position' because if the SDLF goes pair shaped there will not be time to save the biologic stick shaker, if dependent upon 'quick as a cat' fighter pilot reflexes.
Since this is precisely the point where you can expect to find a lot of ejections, you have essentially doubled the injury risk from that alone, even in much higher weight range male pilots.