Well you are correct on it being a Police Action just like Vietnam was not a war but something else. MacArthur also thought he was higher than Truman in how to conduct the conflict in Korea. There was a lot of animosity between the two.
I have heard all the stories about MacArthur's vanity, fact is he was much brighter than Truman, who feared he would enter into politics.
His command was left in the Philippines as fodder, no wonder he didn't trust the politicians.
I remember Movie Tone news showing MacArthur returning and all they could do was complain about the audacity of him having" I shall Return" on the cigarette packs because he didn't say We.