Yes, edit /scp/tickets.php:
//Comments are not required on self-assignment (claim)
if($claim && !$_POST)
$_POST = 'Ticket claimed by '.$thisstaff->getName();
elseif(!$_POST)
$errors = 'Assignment comments required';
elseif(strlen($_POST)<5)
$errors = 'Comment too short';
Just comment that out. (Lines 130 - 136 for me)
You can do the same thing to Lines 91 - 95 to disable the requirement for Transfers if you wish as well.