Verticals are great to level a shot, and most times the picture looks ok than. But sometimes you can't only trust those measured things. You more need to trust your eyes!
And it definately looks unlevel in your version, I have the feeling, the white tower in the background is the Leaning tower of Pisa
Photography is still a art (and yes, it also is on this site!
), and you need to trust your eyes on how the photo looks like, rather than on facts! (but I am also sure that if you measure your photo in a big version, you would also see that the verticals need about 0.5 degrees CW
Anyway have one thing in mind. the screeners probably do not know the airport, neither anything about the picture. They only see the final result. And that is what they have to judge. And they have no tool like PS
to see some verticals or whatever. They can only trust their eyes. And this is good, as is said above the most important fact is that the photo needs to look good as no "normal" visitor of this site will ever check if the verticals are ok. He will look the picture and (hopefully) say: nice picture!