function SQ7_KleoRemoveActivityReplyComm() {
	$user = wp_get_current_user();
	if ( in_array( 'author', (array) $user->roles ) ) {
	    //The user has the "author" role
	    $output = '';
	    if (is_user_logged_in()) {
	        $output .= '<style type="text/css">
	        #buddypress div.activity-comments form.ac-form {display:none !important; }
	        </style>';
	    }
	    echo $output;
	}

}
add_action('wp_head', 'SQ7_KleoRemoveActivityReplyComm');