the very last passenger to be processed

What is your question?

"This person we look at: has he already to have been processed at the airport?"--would not be correct English.

I would also point out that the phrase: "This person we look at . . ." is clumsy English, and would be unlikely to be used by a native speaker of English.

Perhaps if you could give a more comprehensive explanation of what you are trying to say, someone could give you a better way of saying it.

Please look at the subject (heading)
This is what I'm referring to.

"The very last passenger to be processed" is a perfectly acceptable locution in the English language.

You have done nothing to make clear what question it is that you want answered.