He isn't considered a defenseless player in that situation. The NCAA may want to look at tweaking that rule a bit because it happens quite often.
Just to update todays paper says Stanford is awaiting final word from the Pac 10 on the play but the writer seems to think that Stanford appears to have been told it SHOULD have been a penalty. In fact they apparently sent tape of 3 separate plays in the game where Owusu was hit in the head. Harbaugh says the one that knocked him out "appeared to be helmet to helmet" and he took "several shots to the head in the game. " He's listed as day to day but I would be surprised if he plays against USC the way the article is written it seems they'll hold him out for precautionary reasons.
From what I found online the NCAA changed the rule in 09 so that conferences have to conduct a film review of any personal fouls in the games, even if they weren't penalized in the game. It gives them the option of suspending a player for a hit even if the hit was not penalized. It says they are trying to curb helmet to helmet hits. Apparently last year Ohio State had a safety suspended one game for a hit on a WR who was on his way down with the ball when drilled in the head. I didn't see that play but the description sounds very similar to what happened to Owusu so I'm assuming that's why Stanford thinks the Pac 10 will suspend the guy who hit him.
I was glad to see that Chip Kelly has been reprimanded for his comments to Erin Andrews at halftime. Kelly was asked why he was so upset about the clock controversy at the end of the half and he said "I think Jim(Harbaugh) and him(the ref) have friends." IN other words implying Stanford was getting calls because the ref was friendly with Harbaugh. They said reprimanded I don't know if the NCAA can fine coaches for stuff like that, in the NFL he'd have been fined for suggesting the refs were favoring one team.
The play that got him ticked was the game clock ran down to 0 at the half and Oregon started running out on the field, but the refs put 2 seconds back on the clock and Stanford kicked a FG to end the half. Kelly said the clock ran out, but it only did because the timekeeper, who works for Oregon, didn't stop the clock. Harbaugh was standing inches away from the ref and signalled for timeout with 2 seconds left, the ref signalled to stop the clock, but the timekeeper didn't stop it. So putting the 2 seconds back was not favoritism, they were simply undoing the "mistake" by the timekeeper.
Oregon is really good, they took Stanford apart in the 2nd half. Will be interesting to see how Stanford comes back against USC. The Harbaugh rivalry with Carroll is of course now over so it remains to be seen if Stanford will be as jacked up this year as they were last year when they hammered USC.