Honestly the "Shit!" is good communication. Breaking composure and normalcy can ensure everyone hearing the message treats it as urgent. That might make the difference when seconds are on the line.
The US is more loose on ATC phraseology than the rest of the world. The "shit" was probably the startle effect, but "cancel takeoff clearance" is the wrong call for the situation.
Standard when the aircraft is already moving: "Delta 1943 stop immediately, Delta 1943 stop immediately".
The "cancel takeoff clearance" call is supposed to be only used when the aircraft has not moved yet. Like: "Delta 1943, hold position, cancel takeoff clearance, due to xxxx"
