So according to this writer, at an altitude of 35,000 feet, the air flow of the air-cooled system will be reduced to 40% of the sea level. That maybe correct but what he very conveniently forget to mention is that the corresponding air temperature drops as well.
So the basic question is why do you need certain air-flows? You need certain air-flow because you want certain amount of heat to dissipate from the on-board system/s of the fighter. But this air-flow will be varied by the system taking into account the outside air temperature. At an altitude of 35,000 the outside air temperature is usually around -40° C to -57° C. So technically you do not need the same Air 'Flow rate' at higher altitudes than the Flow-rate required at lower altitudes. In other words, less Air-flow would be required at higher altitudes to dissipate system heat due to lower external temperatures.
Not only this, the onboard fighter-jet systems components can be manufactured using gallium nitride instead of Silicon as Gallium Nitride components can withstand very high temperatures .