Well, currently, as an example:
I have profile A and profile B. They are not friends.
If A goes to the settings and sets "who can post to my profile" to "me only", then B can't post anything on the timeline (correct), AND can't comment on any timeline posts (incorrect).
If A goes to the settings, and sets "who can post to my profile" to "friends/anyone", then B can both post on A's timeline and leave comments to A's posts.
I'm not sure whether this is a bug just on my installation of UNA, but I'd like to decouple that, and let everyone comment on everyone's posts regardless of whether they let people to post new timeline posts to their profile or not.
As an example, I, as an admin don't want to let anyone post on my timeline, except for myself. But, when I post something, and promote it so that everyone can see it (even non-friends), nobody can leave a comment. It's either one or the other.