No, there's no stipulation that says they can't receive points in the Nationwide series. We never made that a rule after NASCAr changed its points policy.

As long as Hornish has a full-time ride that is in the top 35 in the Cup series, he is considered one now.  Hornish is full time until the end of the year unless something else happens with that ride.

The Claim Jumper bonus

The claim Jumper bonus began in 2007 to replace the Truck bonus option. A claim jumper used to be called a Busch-wacker when the series was sponsored by Busch. These drivers are in the top 35 in the Sprint Cup standings and have a full time ride. These drivers generally perform better than regular Nationwide series drivers. The season is divided up into three claim jumper segments. During each segment, you can only use each bonus driver once. You can still pick that driver if they appear in another class during the season. You will have to wait until the next segment before you can use that driver again. If you choose the same bonus driver twice during a segment, you won't receive any bonus points for that particular driver in the race. You can see which drivers you've chosen so far on the Claim Jumper bonus grid which lists everyone's bonus picks. You can link to it from the main menu and from the Nationwide picks form. You can not choose that driver if you already picked him in another class in the same race. If you do, you will receive 0 points for the bonus option. You will not be notified of the error. It is up to you to choose correctly. If you choose a bonus driver and he does not make the field, it will still count for your one pick during the segment. 

Where does it say they can only receive Nationwide points?

Oh well, guess I changed it in one place and not the other.

Well soon we aren't going to be having claimjumpers anymore.  I'll make an announcement on that soon, although the council members know about that.