An old motor is more likely to be damaged by 'heat' than a new one?
I would question that! My gutt tells me todays modern engines are MORE likely to suffer damage than the old ones. Alloy heads being one reason, tighter specs, more precise engineering, etc.
But even at that 250 Deg. F by itself is not a 'killer temp'. Around 300 Deg. F for
OIL TEMP is bad news, at that point it starts to break down. But at 250 Deg I doubt that it's lost any lubricity and in fact may be performing better than ever.
However the KILLER thing about THIS overheat episode was the LOSS of water from the radiator hose coming off. The WATER TEMP gauge will read MUCH lower than actual engine temp with no water in the system. 250 Deg was the 'tip of the ice berg' as to real engine heat in this case.