If the profiles were in their own directory, like domain.com/profile/user1, it'd be easy to exclude /profile/ in robots.txt. However, your profiles look like they're off the root. In your software system, is there any way to add a noindex tag to profile pages, or make any type of control over indexing of types of pages?
Is there one main section (folder) of your website that has content that you want optimized? You could also set up a campaign for just that folder, such as domain.com/myimportantcontent/.