That wouldn't seem to apply to lone suicide bombers, since the worst consequence for them comes if they don't get caught. And if they were caught, they could at least detonate in the airport and cause some havoc.
It could also allow them to gain control of the aircraft (maybe, depending on whether they can persuade the people on board that they aren't planning to crash it into anything).
Suicide bombers generally aren't rational folks who multiply "number of infidels I can kill" versus "chance of being caught" though. And we should be thankful that they aren't so rational.
It makes me think that we're doing a pretty good job of keeping most of them out of the country in the first place. Otherwise I think we'd be seeing a rash of smaller scaled, highly targeted incidences like this.
The author is absolutely right. The non-dangerous category is part of a knee-jerk reaction to simply "do something" rather than to do something effective.
And even if it were the only consequence, it would therefore be the worst (and the best).
Either a humiliating failure to detonate, or a humiliating detonation that kills only them, and slowly, like that guy who tried to drive a truck bomb into Glasgow airport.