Are you guys sure of these links not being visible to Google?
I mean, FORUMS allow Google/Yahoo,etc.. Spiders to crawl as exceptions without any need to be logged in.
To make my point, search the URL of that profile in Google.. If you click the link Google provieds, you will be asked to LOGIN, however, if you click the CACHED link (bottom right of the result), the profile will show up without any need of logging in since that is Google's cached copy.
yes, forum admins can set their forums to allow bots to crawl without loging in. But, unless it is set up by default on the forum scripts (I don't know, never run a forum), I will say why bother? there are simply so many public profiles out there.