I think I already know the answer to this, but a client is asking me if they create a block on a page that has permissions set to not allow guests to see, does that mean that search engine bots are unable to index it? I don't see anything in their documentation.
Yes - you are right. Search engines won't be able to see.
However you can test easily to be 100% - use the Fetch as Googlebot tool in Google Webmaster Tools.