I tried adding <if condition="THIS_SCRIPT == 'member'"> to headinclude template with my customized keywords and descriptions but only problem is getting the specific username under those keywords and descriptions.
$bbuserinfo[username] will display name of the user who is viewing user profile and not the user profile (username).
viewing following link ->
http://forums.techarena.in/member.php?u=954 as a guest user will display Unregistered in meta tags.