Lots of advanced AA units mostly of Russian origin were looted during Hillary’s War and found their way - according to numerous reports - into the Sinai and beyond.
Were these only manpads or did Libya have high altitude SAMs? In Reagan’s time they did, so it is safe to assume that Qaddafi still had Russian SAMs which would be able to shoot down airliners.
One does not just put one of those SAMs on the back of a Toyota and drive across North Africa, into Egypt and across the Suez into Sinai.
There are people on the lookout for this stuff.