If you look at that picture you’ll notice that the Hornet has little condensation clouds forming on the fuselage. This is the start of a “Mach Diamond” that forms as the aircraft nears the speed of sound. So chances are the guy with his back turned is looking at something else, and the sound of the Hornet just hasn’t reached him yet.
The USAF Thunderbirds have a part of their routine called a Sneaky Pete. One Viper will fly low and slow in front of the crowd. When it passes crowd center a second will blow by at transsonic speed (just below the speed of sound) and make everyone’s heart jump into their throats. There’s a version of this where the second Viper approaches from behind the crowd too ...
I’ve actually seen, no, experienced, a Sneaky Pete performed by a B-1B. I’m pretty sure my insides were still rattling and vibrating 5 minutes later.
That is awesome and I would love to experience that!