I assume the "light aircraft" were parked on the "GA" side of OERK. When I say "GA", it's really an area set aside for the princes' jet propelled playthings. The only other airfield nearby is OERY and that's military, unless you want to include the ~10,000FT strip about 50KM NE of Riyadh that no-one talks about.
It would be much easier to carry out such an operation outside KSA as not much goes unnoticed in the Magic Kingdom. Someone (probably quite a few people) must have known what was going on.
Glad I'm not there any more.