It's actually simpler than that. No need to share anything.
Person A posts something only to "Followers". Person B, C, D, and E follow A.
Usually: B will only see comments posted by A and B. C will only see comments posted by A and C. D will only see comments posted by A and D. Etc.
But well, Laura already linked the bugreports, so, as you see, it's known.
Oh, and as Laura said, this can be avoided by posting to Public instead.
Patience, and best of luck to Evan (and whoever can help him) fixing this =)