I don't know where all this serve and protect stuff is coming from.
There are several court rulings that basically say police are not obligated to serve or protect anyone individually, their job is strictly law enforcement and to arrest law breakers.
DeShaney v. Winnebago County (1989)
Castle Rock v. Gonzales (2005)
That's not to say what this cop did wasn't a crappy thing to do, but I can't help but wonder why 911 dispatch would send a cop instead of an ambulance to respond to a heart attack/medical call for help.