Not to make an argument for or against the proposition being considered, but those two purposes are not mutually exclusive.
An argument in favor of the proposition is that if a mass killing were undertaken suddenly and directly, social resistance would be equally sudden and direct, an undesirable situation for the would-be Marxist revolutionary. Better to have the effect be long and drawn out, with many private individuals encountering their demise one at a time, not in the shocking horror of a mass death camp (the original Weather Underground vision), but in the individual quietude of a hospital bed with family and friends. How humane.
An argument against the proposition is that while Marxism uses racial themes to motivate population blocks, it is an equal opportunity destroyer. Assuming a plot of the magnitude you suggest really exists, it would be steered by a Soros-like individual, and geared not to the destruction of whites per se but to leaders of the conservative middle class, arguably also a population more likely to be flying than the unwashed poor. But it would bee too dull a weapon to accomplish its purpose, as many in the highest reaches of the conservative middle class (and above) have alternatives to commercial flight.
All I know is this. I have a consulting job with the state right now that concerns our readiness for radiological disasters. There are people here, in our state government, who do dose assessment for a living, who do not trust the backscatter devices, despite the published data. And published data may not matter even if it’s theoretically correct because, based on experience with other such devices, if the calibration is off, and the image quality is poor, the ill-trained TSA staff will probably just turn up the intensity to get a better image, much to the dismay of the victim’s dna, I’m sure.
I wish there was proof these measures were stopping terrorism - I fear that's not the case...