No need to edit the core file. The bp_attachments_current_user_can filter can be used here.

add_filter( 'bp_attachments_current_user_can', function( $can, $capability ) {
if ( 'edit_avatar' !== $capability ) {
return $can;
}
// This will let all users upload an avatar (not just logged in members).
$can =…[Read more]