How can i achieve this that google no longer indexes usernames. I have blocked the memberlist and profile pages but searching for generic usernames in google still returns some hits from names in posts.
As we are working with real names I want to give our members the privacy they deserve
If you want the post content indexed, the user names are going to be indexed with it. I don't think you can get around that. You can only disable indexing of the profiles themselves (and I'd simply recommend disabling guests from viewing profiles in that case).