He's supposed to be a sniper. In fact he claims to have been in the most elite sniper squad in the Republic. He can't use sniper rifles (last time I checked). It's silly. Bioware needs to match story with mechanics more I think.
Yea, it's one of the bigger holes in how the companion weapon choices got laid out there. It doesn't seem like it would be too hard to actually let him use Sniper Rifles either.