Based on this, I just had an idea, to prevent further misunderstandings. Why not add some sort of an icon beside a username, showing that certain profile pages are being kept private? Probably not the best picture, but it pretty much sums up my idea:
I don't think that's possible in the XenForo software. Remember, this forum is based on a software, not made from scratch. You could make an account on the XenForo Community and post here for that suggestion.
If you really want that plug-in, look at other XenForo forums and think how they are going to feel about it. Tell it on the original XenForo, the one that is a XenForo forum based on a Xenforo forum. Confusing right? Here you go https://xenforo.com/community/ EDIT: https://xenforo.com/community/forums/xenforo-suggestions.18/ use that link for a shortcut to the suggestions section.