Sure. Most would rather speak to someone in a suit than in someone wearing their underpants on the outside and with full-on nationalistic emblems on their spandex uniform.
What version of Captain America has underpants on the outside? I'm not familiar with that version of the character's outfit...
On a more serious note, the point of the comment is that if the context allows you to be taken relatively seriously in a superhero outfit, it might not be a bad idea to attract people to a booth... Yes, those contexts might not be extremely common.