There is no doubt MacArthur was wrong in his analysis of what China might do....and not only MacArthur but his staff (including intelligence officers) simply had little respect for the military capabilities of china....referring to them as laundrymen....their perspective on China was based largely on China's military performance in WWII which was very poor.
But also...........one must consider all the limitations placed on MacArthur by Truman i.e. refusing to let our AirForce go beyond the Yalu River and knock out China's ability to invade N.Korea etc.etc. basically the whole fallacious and disastrous policy of 'limited war' was begun by the Truman Administration and a pc communist ridden state Dept. which was a huge, huge security leak as in they were thoroughly penetrated by Russian Intelligence agents.
General Douglas MacArthur Defends His Conduct in the War in Korea | Teaching American History
...the US did not want a war with China--that would've been really stupid---we couldn't beat tiny North Vietnam...you don't want to go dropping A bombs for nothing--especially for a
civil war....you can't beat China--too big--too many people
...most wars are ''limited''
my father fought at the Chosin
temps down to 30 below [ not wind chill ]...snowy, icy. hilly terrrain
after fighting for 2 days, with little sleep, they went ''cross-country'' in those temps to save Fox Company around 2 Dec
however, so what if the North took over?...North Vietnam took over the South
the communists took over Laos and Cambodia, and Cuba--no big deal