It may have taken a couple of seconds for the brain to process what happened and the mouth to speak the words. As it stands it’s not entirely his fault they used the network delay system (I believe the standard is 5 seconds) in an attempt to prevent this from airing live. Obviously something or someone screwed up and it aired. I don’t think Shep had a magic button to press to stop it’s airing, likewise the only reason it stopped airing had little to do with Shep’s “Get It off” comments and the timing of them.
The fact he had no control over it’s being aired is clearly evidenced in the fact that he was continually requesting it be taken off (rather than just doing it himself). There was someone sitting elsewhere who had control of that and either didn’t realize what had happened or was in shock over seeing it themselves. Of course this day in age there is also the aid of computer programs to help with video processing (i.e. youtube uses it every time a video is uploaded).
Now I saw you commented elsewhere that perhaps a 10 second delay might be used. Which given that children my be in the room watching wouldn’t be a bad idea depending on their age.