He doesn't have a sponsor that advertises there, simple as that. Same reason you see his driver suit all blacked out in his starting lineup photo on the FOX tv broadcasts. No big deal.
Yeah its still bs... He belongs on that page!!! We need some top 10's and start qualifying better and Robby will get some respect again... Its sucks watching him struggle alot... Wouldnt it be nice to have a teammate to compare setups
Actually, last time I checked, his stats were missing as well. Click on his name and you will not see any 2010 stats calculated into his career stats. Even part time drivers have this feature. Seems the site might actually have a flaw of some sort.
Ultimate Racing History is great too. Racing-Reference seems somewhat better organized, and has better search options, but Ultimate Racing History has stats for some series and drivers and races that the other doesn't.