So I just post here the solutions to show the subscribers profile on the author.php page.
I found it after a lot of headaches on the regular Wordpress forum here
So for WPMU :
To get around this problem, you'll have to modify wp-include/classes.php function handle_404().
Find this line:
if ( (0 == count($wp_query->posts)) && !is_404() && !is_search() && ( $this->did_permalink || (!empty($_SERVER['QUERY_STRING']) && (false === strpos($_SERVER['REQUEST_URI'], '?'))) ) ) {
and include negative qualifier for author pages:
if ( (0 == count($wp_query->posts)) && !is_404() && !is_author() && !is_search() && ( $this->did_permalink || (!empty($_SERVER['QUERY_STRING']) && (false === strpos($_SERVER['REQUEST_URI'], '?'))) ) ) {
thanks to Codersteve !