As if people would allow bladed lizard monsters from outer space to travel on their planes, no matter how peaceful they are. If Hork-Bajir traveled on planes, it would be their own, with human pilots, but no other human presence on the plane. Humans are racist, afraid of what they don't understand, and would rather not take chances with giant bladed lizard aliens. Besides, unless they have Toby level intelligence, a Hork-Bajir "sky marshal" can be fooled pretty easily.
As to me, I think that the Yeerks would have a rallying effect on the Middle East. In fact, it would drive people into the arms of the religious extremists who advocate that the Yeerks are satanic creatures and must be wiped out, possibly even the Controllers within these terrorist groups convincing them that they've sided with the "infidels" across the ocean so that there will be more armed conflict to divert attention away from them and focus it on America, making Earth much easier for conquest.
