“Not only is it improbable, it’s too easy to get caught.”
Everything is improbable until it happens and people willing to blow themselves up are not concerned about getting caught. 9/11 was improbable too.
People who are willing to blow them selves up is impossible to prevent, but that part doesn't even enter this conversation about RC planes.
The 911 scenario was easy to carry off, box cutters were not prohibited items at the time.
Heathens slicing up flight attendants may seem hideous to you and I, but to them it is a method...which we now recognize.
They obviously had a high expectation of success, ergo it was not improbable.
You can't say that in your scenario.