I agree. I hate Trump as much as anyone else, but if a President I liked did this, it wouldn't be the end of the world.
In principle, I don't mind if a space mainly used for events, with chairs placed there often, should be hardscape. It's not as if lawn can't be put back there in the future. Lawn isn't a heritage tree or rose shrub.
To be fair though, the photo makes it look pretty huge as an expanse of paved area.
Restaurants, too!
Even if you resist the urge to buy books and souvenirs at the airport, arriving 3 hours early will probably mean you need to eat a meal that you would have otherwise eaten at home or at a cheaper restaurant.
And even if you're not hungry, you might choose to sit in a comfy seat at one of the airport bars, having a few drinks and appetizers.