I can select a post within a topic and move it to a new or existing topic. I can also change it’s ownership. But, I can’t change that one post to a PM. I can change a whole topic to a PM. But, I can’t change one post to a PM.
Someone posts a reply in a topic and I want to remove it and explain why to them, privately. An easy approach is to turn that one post into a PM and then reply to it privately, outside the topic.
Have the same “change to PM” functionality available for both topics and posts.