I don't want to see him review any genre that he isn't into or doesn't understand or want to understand.
SSBB was a step back in the Smash Brothers series, but all the complaints I had about that game he barely even touched on. All the complaints he had about that game seemed to be complaints about the Wii, or complaints about Nintendo, or complaints about fighting/party games. So while I didn't think SSBB deserved the sheer amount of praise it received from the fanboys I also felt like Yahtzee completely missed the point. As much as I love watching him tear over hyped games to pieces it isn't fun if his rage is pointed in the wrong direction.
I'm glad he's not reviewing StarCraft2. It's a brilliantly made strategy game with lots of depth and balance, polish, and developer support. It's also only a fun game for people who are into that kind of game. The single player has plenty to tear apart and I'd be more than happy to hear his take on the story, but once we get to the gameplay review he simply wouldn't have anything substantial to say, any praise would be worthless and any insults would be equally worthless. It would be misdirected and just frustrating to anyone who actually knows anything about the series.
Of course, at the end of the day, he can review what he wants, if he wants to try to review a genre he's never played before or never really enjoyed than more power to him, but what needs to be understood is that many problems he would have getting into it is more his problems with the genre and less with the game itself. It's like what he said about Skate 2: "They don't need me kicking their door down and demanding to be accommodated".
So tl;dr He should only review titles that are in the genre that he wants to play. It would lead to funnier and more legitimate insults.