@hypolite
The comment is itself a creation. Just because the owner does not think it fits their conversation does not mean the author has to lose their production or the ability to show it to their own followers.

However, I agree that it is better that the owner be responsible with distributing replies to the original recipients and that they be able to exclude a subtree from this procedure. But in that case I think the comment should be turned into a quote-share and normally distributed to its author's followers rather than deleted.