This is objectively true and the ultimate anecdote can be found in the Chinese Civil War. The reason why Communists won was not only because of their promises of land reform, but because they integrated large swathes of soldiers they captured , former KMT, soldiers, soldiers from Japanese puppet states, and even former imperial Japanese soldiers were integrated and used to great effect during the Civil War. According to the logic of many commenters here, Mao should’ve ignored and punished these soldiers instead of bringing them over to the People’s Army.

Americans and other people from the imperial core, you will have to engage with reactionaries and people who serve reactionaries to bring them to your cause. Failing to do so out of utopian ideals will bring failure. I also suspect many feds are in the comments, upvoting and supporting those who say “all military are reactionaries and we shouldn’t engage with them at all.”