MacArthur is likely to discount any intelligence that contradicts his thoughts. The only thing I can see is that the Pentagon reads those same reports and instructs Mac to make immediate plans. But to be honest, Mac would probably ignore them. I don't see it preventing the disaster, but it may mean he'll be removed from command earlier after the attack happens and at less controversy.
Furthermore, I don't think Truman can politically not advance to the Yalu. It would make him look weak on Communism in US domestic politics. If he says he must stop lest the Chinese Communists attack UN forces, he'll look like a fool. No one believes that China would be a threat to the US Army at that time. The actual success of PRC forces was very sobering.
To prevent disaster in north Korea, there are only two options.
1) Secret negotiations with the PRC that UN forces will not cross the Yalu, and that all forces - except for Korean troops - will withdraw south of the 38th parallel after North Korea is defeated, and that no hostile action will be taken against the PRC.
2) MacArthur is somehow not the commander after the advance to the Yalu is made. That person could take the actions MacArthur should have, but didn't.