I'm not sure you can say 'debunked'. most of the sources i saw claim he said it in a speech in 1954. He still could have said it. I started reading how "individualism" was being used in different contexts during that time period, but i got bored.. but its possible he meant 'individualism' as say pro-socialism/pro 'world governement' vs. seperate gov type thing. I'm probably not saying that clearly.
Out of all the elements of the quote "it is necessary to remove from the minds of men their individualism" is what seems to jar the most, given what we know of Chisholm's views on the freedom of individuals to mature free of the dictates of the arbitrary authority of parents, local cultural norms and religious dogma.
Most people reading that quote would assume would assume that "individualism" meant something like "libertarianism" does today - that is, a political position in opposition to communitarianism.
But "
individualism" actually has a different nuance of meaning in the context of psychoanalysis and personality theory. Traditional Freudian theory held that personality development was primarily inherent to the individual, and that social factors were secondary. Among critics of this view (called
Individualism) in the mid 20th century were the neo-Freudians such as Eric Fromm and Harry Stack Sullivan, who held that social, cultural and interpersonal influences - parents, religion, local culture, etc were far more important factors (both positive and negative) in the development of a mature, non-neurotic, fully realised
individual. Chisholm was definitely of that latter view.
So "it is necessary to remove from the minds of men their
individualism" in this context does not mean removing
individuality - on the contrary, it could mean something like "we need to recognise the negative impacts of social institutions on psychological development, rather than pretend that these are not important".
Obviously, we would need to see the quote (if it exists) in its context to see exactly what Chisholm meant by it. But I suspect that part of the problem might be confusing the words
individualism (a theory of personality development) with
individuality (a state of free personhood).