> No, it is not. Nobody should be able to influence air traffic in that way just because she/he understands the transport layer.
I hear you. But it is the reality of the world. There comes a time when everyone realizes that the boundary between civilized behavior and uncivilized behavior is just a convention. I think of it as the final stage of moving from childhood into adulthood.
For example, you could go into the hardware store and buy a couple of bags of fertilizer, some stump remover, a bag of charcoal for the grill, some food for the roses, and six quarts of motor oil. Are you going to do some gardening and grilling over the weekend or going to blow up someone's house? The materials work for either activity. Maybe you rent a moving van over the holiday weekend. Helping a buddy move? Or mowing down tourists at a crowded venue?
People who choose to be evil will be evil. There isn't anything you can do about them but you can build defense in depth on various other ways.
In the case of air navigation you have a pilot in the cockpit who is supposed to be paying attention. They can takeoff, navigate, and land with nothing more than their eyeballs, a compass, and some paper charts. All the other gizmos help certainly but they aren't essential[1]. When people actively interfere with the other gizmos, whether it is intentionally by transmitting on restricted frequencies, or unintentionally like the delivery truck that shut down Newark Airport because the driver used a GPS jammer to keep the home office from seeing they were taking a break while he watched the planes, it has effects. The rest of the system reacts to minimize damage and risk and the actions themselves bring attention to the people involved.
It is fortunate in my experience that that 90+% of the people in the world are too lazy or simply not wired to be curious about how things work the way they do. You may have noticed from the article that they didn't say how you would interfere with navigation with a "$600 SDR", they just said that you could. Most people reading that will say, "Oh dear that's dreadful! Oh look here's a picture of a funny puppy on the next page."
As I get older and meet more people, it amazes me how rare genuine curiosity really is. The persistence to follow that curiosity in order to develop understanding is rarer still. Life doesn't have a safety net, and trying to give it one to eliminate danger completely is pretty futile.
[1] Ok the pilots in the group are going to jump up and say, without an artificial horizon, an airspeed indicator, and working altimeter and you'll be sorry but even without those you can do pretty well.