Settings vs Code: Can I turn off Broadcast Message through settings?
Well, I can do this via hook_menu_alter():

if (variable_get('custom_no_broadcast', true)) {
  unset($items['node/%/broadcast']);
}


And in I take the link out via hook_preprocess_block():

// If set, attempts to surpess the link to broadcast messages to all group members.
if (variable_get('custom_no_broadcast', true)) {
    $variables['block']-&gt;content  = preg_replace("/&lt;a\shref=\"\/node\/\d+\/broadcast\"&gt;Broadcast message&lt;\/a&gt;/", '', $variables['block']-&gt;
}


Or just turn off the Commons Notifications module.