I am using cb privacy plugin to control access to other fields, however it doesnt seem to work for the system field onlinestatus.
Cool - I'm not using CB Privacy so it's beyond my realm - however, I just went into:
Components > Community Builder > Field Management and added a new [Radio Buttons] field (cb_onlinenow). I set the values (at the bottom) to Show Online + add field + Hide Online.
After saving that new field, I opened the cb_onlinestatus field and set the following 2 conditions as shown in the screen cap:
SHOW (condition 1)
HIDE (condition 2)
Now, if I log in to my public profile, I can go to the EDIT profile link, select the group that contains the Show/Hide field (my case: 'About Me'), scroll down and select to show or hide.
It may not be as simple as pressing a button (maybe a core edit or something else...) but it seems to work for me.
PS your site ezbandpage looks awesome
Thanks!