This is addressed directly in the article. "We're currently running a very limited, US-only test, in which advertisers can include an image as part of the search ads that show in response to certain branded queries."
I think "certain branded queries" are the key words here; if that style of banner is displayed for more generic searches (simply 'Airlines', for example) I think people would quickly become frustrated with the experience and move on.
When searching for a particular airline, being confronted with a photograph of one of their aeroplanes isn't the end of the world.
Well.. it is a banner and the company is paying for it so it is an ad. In my opinion the cleanness of the banner should not interfere with the description of being an ad.
https://www.google.com/search?q=SouthWest%20Airlines doesn't do it for me at the moment, from the UK.