Making your profile private to blocked users is useless as they can just log out and view your profile or create a second account and view your profile. Blocking Communication is only intended to block them from directly contacting you or posting on you profile.
Full Answer
To block a ROBLOX member for any reason you see fit, go to their profile page. Under their character thumbnail, you’ll see a “More” button. Hit the button, and click “Block user.”
Hit the button, and click “Block user.” This adds the user to your block list, which you can manage at any time within the “Privacy” tab of the Account Settings page. Currently, you can block a maximum of 50 individuals.
A blocked persons list in Roblox is limited to 50 per user. This means that someone who employs this function on a regular basis will have to consider unblocking others at some point. If you’ve blocked someone by accident, you might want to unblock them as soon as possible.
The feature was added on October 2, 2014, and allows individuals to take control of who interacts with them by clicking the Block User button. Users might be blocked because of bothering someone, spamming friend, etc.
Blocking clearly states "Block Communication". That means the user can not contact the user , not that the user's profile is not viewable. If someone wants the profile non-viewable, then they need to make it private or friends only. Making your profile "private" only to blocked users is pointless, as I said before.
Blocked users can still see your profile, receive notifications, follow you, etc. As the title says, even if you block someone, they can still be subscribed to the comment thread on your comments, and though it prevents them from posting anything, they still receive notifications/updates on when someone else posts something there. ...