The Barracuda are also really low on defensemen (if seven are on the Sharks, only six are left on the Barracuda), so maybe this is to see if he's worth an AHL contract.
As you say, filling out the numbers. Given the likelihood that Karlsson and Simek get hurt this year, I'd like to have two more Barracuda defensemen going into the season (AHL deals are fine, we have four guys who will be worth a look anyway and the waiver wire should occasionally give us a shot at someone interesting or at least useful).